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Lung

Hansen

Textbook of

Cancer

Textbook of Lung Cancer, Second Edition, published in association with the European Society for Medical Oncology, is a comprehensive and multidisciplinary text, which examines all aspects of this disease, with contributions from a multinational team of authors on etiology, epidemiology, molecular biology, pathology, smoking, detection and management, clinical features, staging and prognostic factors, surgery, radiotherapy and chemotherapy. It provides essential information and guidance for specialist trainees in oncology, and for the many physicians and specialists involved in

Table of contents Etiology of lung cancer • Epidemiology of lung cancer • Molecular biology of lung cancer • Tobacco policy • Smoking cessation programs • Current status of early lung cancer screening • Histopathology of lung tumors • Clinical diagnosis and basic evaluation • Staging, classification and prognosis • Treatment of non-small cell lung cancer • Treatment of small cell lung cancer • Malignant mesothelioma • Summary of treatment • Therapeutic bronchoscopy for palliation of lung tumors • Complications to lung cancer • Quality of life and supportive care • The cost and cost-effectiveness of lung cancer management • The future • Appendix: Chemotherapy

About the editor Heine Hansen MD FRCP is Professor of Clinical Oncology at the Finsen Center, National University Hospital, Copenhagen, Denmark.

Also available: ESMO Handbook of Cancer Prevention Edited by Schrijvers, Senn, Mellstedt, Zakotnik (ISBN: 9780415390859) ESMO Handbook of Principles of Translational Research Edited by Mellstedt, Schrijvers, Bafaloukos & Greil (ISBN: 9780415410915) Lung Cancer – Translational and Emerging Therapies Edited by Pandya, Brahmer & Hidalgo (ISBN: 9780849390210) Image-Guided Radiotherapy of Lung Cancer Edited by Cox, Chang & Komaki (ISBN: 9780849387838)

Lung Cancer

the field of lung cancer.

Textbook of

Second Edition

Cancer

Second Edition

Edited by

Heine Hansen

Textbook of Surgical Oncology Edited by Poston, Beauchamp & Ruers (ISBN: 9781841845074) Lung Cancer Therapy Annual 6 Edited by Hansen (ISBN 9780415465458)

Second Edition www.informahealthcare.com

Lung Textbook of

Published in association with the European Society for Medical Oncology

Textbook of Lung Cancer

Textbook of Lung Cancer Second Edition Edited by

Heine Hansen MD FRCP Finsen Center National University Hospital Copenhagen Denmark

© 2008 Informa UK Ltd First published in the United Kingdom in 2000 Second edition published in the United Kingdom in 2008 by Informa Healthcare, Telephone House, 69-77 Paul Street, London EC2A 4LQ. Informa Healthcare is a trading division of Informa UK Ltd. Registered Office: 37/41 Mortimer Street, London W1T 3JH. Registered in England and Wales number 1072954. Tel: +44 (0)20 7017 5000 Fax: +44 (0)20 7017 6699 Website: www.informahealthcare.com All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the publisher or in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of any licence permitting limited copying issued by the Copyright Licensing Agency, 90 Tottenham Court Road, London W1P 0LP. Although every effort has been made to ensure that all owners of copyright material have been acknowledged in this publication, we would be glad to acknowledge in subsequent reprints or editions any omissions brought to our attention. The Author has asserted his right under the Copyright, Designs and Patents Act 1988 to be identified as the Author of this Work. Although every effort has been made to ensure that drug doses and other information are presented accurately in this publication, the ultimate responsibility rests with the prescribing physician. Neither the publishers nor the authors can be held responsible for errors or for any consequences arising from the use of information contained herein. For detailed prescribing information or instructions on the use of any product or procedure discussed herein, please consult the prescribing information or instructional material issued by the manufacturer. A CIP record for this book is available from the British Library. Library of Congress Cataloguing-in-Publication Data Data available on application ISBN-10: 0 415 38510 5 ISBN-13: 978 0 415 38510 7 Distributed in North and South America by Taylor & Francis 6000 Broken Sound Parkway, NW, (Suite 300) Boca Raton, FL 33487, USA Within Continental USA Tel: 1 (800) 272 7737; Fax: 1 (800) 374 3401 Outside Continental USA Tel: (561) 994 0555; Fax: (561) 361 6018 Email: [email protected] Distributed in the rest of the world by Thomson Publishing Services Cheriton House North Way Andover, Hampshire SP10 5BE, UK Tel: +44 (0)1264 332424 Email: [email protected] Composition by Exeter Premedia Services Pvt Ltd., Chennai, India Printed and bound in India by Replika Press Pvt Ltd

Contents

List of Contributors

vii

Preface

xi

Color plate 1. Etiology of lung cancer Aage Haugen, Steen Mollerup

xiii 1

2. Epidemiology of lung cancer: a century of great success and ignominious failure Peter Boyle, Sara Gandini, Nigel Gray

10

3. Molecular biology of lung cancer Thomas Tuxen Poulsen, Hans Skovgaard Poulsen, Helle Pappot

20

4.

35

Tobacco policy Nigel Gray

5. Smoking cessation programs Philip Tønnesen

41

6. Current status of lung cancer screening James L Mulshine

53

7. Histopathology of lung tumors Elisabeth Brambilla, Sylvie Lantuejoul

61

8. Clinical diagnosis and basic evaluation John J Mullon, Eric J Olson

75

9. Staging, classification, and prognosis Michael Dusmet, Peter Goldstraw

97

10. Treatment of non-small cell lung cancer 10.1 Treatment of NSCLC: surgery Robert J Korst

123

10.2 Treatment of NSCLC: radiotherapy Merideth MM Wendland, William T Sause

136

vi Contents

10.3 Treatment of NSCLC: chemotherapy Athanasios G Pallis, Sophia Agelaki, Vassilis Georgoulias

147

11. Treatment of small cell lung cancer

12.

11.1 Treatment of SCLC: surgery Hisao Asamura, Riken Kawachi

170

11.2 Treatment of SCLC: radiotherapy Christopher M Lee, William T Sause

177

11.3 Treatment of SCLC: chemotherapy Heine H Hansen, Morten Sørensen

184

Malignant mesothelioma Bruce Robinson, Anna Nowak, Cleo Robinson, Jenette Creaney

190

13. Summary of treatment Heine H Hansen

207

14. Therapeutic bronchoscopy for palliation of lung tumors Paul WA Kunst, Pieter E Postmus, Thomas G Sutedja

210

15. Complications of lung cancer Vincenzo Minotti, Michele Montedoro, Maurizio Tonato

218

16. Quality of life and supportive care Jean-Paul Sculier, Anne–Pascal Meert, Marianne Paesmans, Thierry Berghmans

236

17. The cost and cost-effectiveness of lung cancer management William K Evans, Christopher J Longo

247

18.

The future Giovanni Selvaggi, Giorgio Vittorio Scagliotti

264

Appendix: Chemotherapy

275

List of drugs

331

Index

333

Contributors

Sophia Agelaki MD Department of Medical Oncology University Hospital of Heraklion Heraklion Greece Hisao Asamura MD Division of Thoracic Surgery National Cancer Center Hospital Tokyo Japan Thierry Berghmans MD Department of Critical Care and Thoracic Oncology Institut Jules Bordet Brussels Belgium Peter Boyle MD International Agency for Research on Cancer Lyon France Elisabeth Brambilla MD PhD Deptartment of Pathology Michallon Hospital CHRU Grenoble National Institute for Health and Medical Research University Fourier Grenoble Grenoble France

Jenette Creaney MD School of Medicine and Parmacology Sir Charles Gairdner Hospital Perth, WA Australia Michael Dusmet MD FMH Department of Thoracic Surgery Royal Brompton Hospital London UK Williams K Evans MD FRCPC Department of Oncology McMaster University Hamilton, Ontario Canada Sara Gandini MD Division of Epidemiology and Biostatics European Institute of Oncology Milan Italy Vassilis Georgoulias MD PhD Department of Medical Oncology University Hospital of Heraklion Heraklion Greece Peter Goldstraw MD Department of Thoracic Surgery Royal Brompton Hospital London UK

viii List of Contributors

Nigel Gray AO MBBS FRACP FRACMA Tobacco Unit International Agency for Research on Cancer Lyon France

Christopher J Longo PhD MSc BA DeGroote School of Business McMaster University Hamilton, Ontario Canada

Heine H Hansen MD The Finsen Center National University Hospital Copenhagen Denmark

Anne–Pascal Meert MD Department of Critical Care and Thoracic Oncology Institut Jules Bordet Brussels Belgium

Aage Haugen PhD Department of Chemical and Biological Working Environment National Institute of Occupational Health Oslo Norway

Vincenzo Minotti MD Department of Medical Oncology Santa Maria Della Misericordia Hospital Perugia Italy

Riken Kawachi MD Division of Thoracic Surgery National Cancer Center Hospital Tokyo Japan

Steen Mollerup PhD Department of Chemical and Biological Working Environment National Institute of Occupational Health Oslo Norway

Robert J korst MD Daniel and Gloria Blumenthal Cancer Center Valley Health System Valley Hospital Paramus, NJ USA

Michele Montedoro MD Department of Medical Oncology Santa Maria Della Misericordia Hospital Perugia Italy

Peter WA Kunst MD PhD Department of Pulmonary Diseases HAGA Hospital The Hague The Netherlands Sylvie Lantuejoul MD PhD Department of Pathology Michallon Hospital CHRU Grenoble National Institute for Health and Medical Research University J. Fourier Grenoble Grenoble France Christopher M Lee MD Department of Radiation Oncology University of Utah School of Medicine Huntsman Cancer Hospital Salt Lake City, UT USA

John J Mullon MD Division of Pulmonary and Critical Care Medicine Mayo Clinic College of Medicine Rochester, MN USA James L Mulshine MD Rush University Medical Center Chicago, IL USA Anna Nowak MD School of Medicine and Pharmacology Sir Charles Gairdner Hospital Perth, WA Australia Eric J Olson MD Division of Pulmonary and Critical Care Medicine Mayo Clinic College of Medicine Rochester, MN USA

List of Contributors ix

Marianne Paesmans MSc Data Center Institut Jules Bordet Brussels Belgium Athanasios G Pallis MD PhD Department of Medical Oncology University Hospital of Heraklion Heraklion Greece Helle Pappot MD Department of Oncology Copenhagen University Hospital Copenhagen Denmark Pieter E Postmus MD PhD Department of Pulmonary Diseases Vrije Universiteit University Medical Center Amsterdam The Netherlands Hans Skovgaard Poulsen MD DMSc Department of Radiation Biology Copenhagen University Hospital Copenhagen Denmark Thomas Tuxen Poulsen MSc Department of Radiation Biology Copenhagen University Hospital Copenhagen Denmark Bruce WS Robinson MBBS MD FRACP FRCP DTM&H FCCP

National Research Centre for Asbestos Related Diseases School of Medicine and Pharmacology Sir Charles Gairdner Hospital Perth, WA Australia Cleo Robinson MD National Research Centre for Asbestos Related Diseases School of Medicine and Pharmacology Sir Charles Gairdner Hospital Perth, WA Australia

William T Sause MD LDS Hospital Radiation Center Salt Lake City, UT USA Giorgio V Scagliotti MD Department of Clinical and Biological Sciences University of Turin Orbassano, Turin Italy Jean-Paul Sculier MD PhD Department of Critical Care and Thoracic Oncology Institut Jules Bordet Brussels Belgium Giovanni Selvaggi MD Department of Clinical and Biological Sciences University of Turin Orbassano, Turin Italy Morten Sørensen MD The Finsen Center National University Hospital Copenhagen Denmark Tom G Sutedja MD PhD Department of Pulmonary Diseases Vrije Universiteit University Medical Center Amsterdam The Netherlands Maurizio Tonato MD Regional Cancer Center Poloclinico Hospital Perugia Italy Philip Tønnesen MD Department of Pulmonary Medicine Gentofte University Hospital Hellerup Denmark Merideth MM Wendland MD Department of Radiation Oncology Huntsman Cancer Hospital University of Utah Salt Lake City, UT USA

Preface

Since the publication of the first issue of this textbook in 2000, the epidemiologic features of smoking have undergone continuous changes and the worldwide intensification of the battle against tobacco consumption is changing the geographic pattern. In the USA, some western European countries, and Australia, the incidence of lung cancer is decreasing among males, while the disease continues to increase among females. In the southern and eastern parts of Europe, lung cancer is on a rapid rise, and a similar pattern is seen in highly populated countries like China, Indonesia, and Japan. Other regions of the world, such as the Middle East, Africa, and South America, show the same dismal picture. Worldwide, the annual number of new cases of lung cancer is estimated at more than one million and is expected to increase to ten million in 2025. Fortunately, the political efforts to reduce the use of tobacco are getting increasing attention in many countries and the statistics are now showing the first positive results.

Among the epidemiologic changes we also see a change in the histopathologic pattern, with a relative decrease in squamous cell carcinoma and a rise in adenocarcinoma. Lately, important new information as regards the biology of lung cancer is emerging, including new treatment approaches. The result is a slow, but steady improvement of the overall management of lung cancer based on an increasing use of combined modality therapy, consisting of surgery, chemotherapy, and radiotherapy applied concurrently or sequentially in early stage disease. Furthermore, new techniques are gaining ground, both within surgery and radiotherapy, and targeted medical therapy is being offered to more and more patients. The textbook brings up-to-date information about lung cancer, based on worldwide experience, for the use of the many physicians involved in this field. Heine H Hansen

Color Plates

(a)

(c)

(b)

Figure 8.5 18F-FDG-PET scan with CT fusion demonstrating a primary adenocarcinoma in the left upper lobe (a), with contralateral hilar metastasis (b). (c) Coronal 18F-FDG-PET without CT fusion, demonstrating no extrathoracic involvement. Transbronchial needle aspirate of the right hilar lymph node confirmed metastatic adenocarcinoma with stage IIIB NSCLC assigned.

xiv Color Plates

(a)

(c)

(b)

Figure 8.6 18F-FDG-PET scan with CT fusion demonstrating a primary adenocarcinoma involving the left upper lobe with ipsilateral mediastinal lymph node metastasis (a), and left adrenal mestastasis (b). (c) Coronal 18F-FDG-PET without CT fusion demonstrating mediastinal and extrathoracic (left adrenal) involvement. CT-guided biopsy of the left adrenal confirmed metastatic adenocarcinoma with stage IV NSCLC assigned.

Color Plates xv

Figure 9.13 The nodal chart established by the American Joint Committee on Cancer (AJCC) and the Union Internationale Contre le Cancer (UICC) in 1997.3

Figure 11.2.2 Anterior-posterior digitally reconstructed radiograph (DRR) illustrating a typical radiation portal which includes the primary tumor mass and adjacent hilar/mediastinal lymph nodes.

xvi Color Plates

Figure 11.2.3 Conformal radiotherapy planning techniques allow escalated radiation doses to be delivered safely with simultaneous sparing of surrounding critical structures. In this example, a combination of anterior-posterior and oblique fields (four fields in total) are utilized to decrease radiation dose to the nearby spinal cord.

Figure 11.2.4 Right lateral digitally reconstructed radiograph (DRR) illustrating a typical portal used for prophylactic cranial irradiation.

1

Etiology of lung cancer Aage Haugen, Steen Mollerup Contents Introduction • Carcinogens in tobacco smoke • Environmental tobacco smoke • Air pollution, radon, workplace exposure, and viruses • Genetic susceptibility and lung cancer etiology • Females and lung cancer susceptibilty

INTRODUCTION Lung cancer, which was rare at the beginning of the 20th century, is now a global problem. It is the most frequent cancer in the world.1 Presently, 1.2 million people die of lung cancer each year and the global incidence of lung cancer is increasing. A major contribution to this trend comes from the former socialist economies and developing countries where smoking rates are still high. Consequently, lung cancer will remain a major cause of cancer death worldwide in the 21st century even though the prevalence of tobacco use has declined in many high-income countries. That carcinogens in tobacco smoke play a major role in lung cancer is unquestionable. About 85–90% of lung cancer patients are smokers.2 However, lung cancer also occurs in people who have never smoked, and this implies that factors such as environmental tobacco smoke (ETS), environmental and domestic air pollution, work-related risk factors, radon exposure, and viruses may also have an impact on lung cancer incidence rates. In addition, since fewer than 20% of smokers will develop lung cancer in their lifetime, inherited predisposition may be an important component. CARCINOGENS IN TOBACCO SMOKE Lung carcinogenesis is mediated through an interaction between several putative carcinogens. A smoker inhales gas-phase smoke (so-called ‘mainstream smoke’) as well as particulates (tar). Cigarette smoke is a complex mixture of compounds and more than 4000 compounds have been identified in tobacco mainstream smoke3–7 (Table 1.1). Studies have led to the identification of 60–70 carcinogens: polycyclic aromatic hydrocarbons (PAHs), heterocyclic hydrocarbons, N-nitrosamines, aromatic amines, N-heterocyclic amines, aldehydes, various organic compounds, inorganic compounds such as hydrazine and some metals, and free radical species. Table 1.2 lists likely causative agents for lung cancer.

Available evidence indicates that carcinogenic PAH compounds and the tobacco-specific carcinogen NNK (4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone) are of major importance in lung cancer induction in smokers.8 Most studies on tobacco smoking genotoxicity in the lung have focused on these compounds. They are strong carcinogens and tobacco contains relatively high amounts of PAHs and N-nitrosamines. However, compounds such as aldehydes, butadiene, and benzene, which appear to have lower carcinogenic potential, are found in much higher quantities in tobacco smoke. PAHs are formed by incomplete combustion of tobacco during smoking. PAHs, particularly benzo(a) pyrene, induce tumors of the lung in laboratory animals by various routes of administration. Furthermore, studies have demonstrated that human lung tissue can metabolize PAHs to reactive metabolites that can interact with DNA, forming mutagenic DNA adducts.9 DNA adduct formation is thought to be the primary initiating event in carcinogenesis and may be predictive of lung cancer risk.10,11 PAH–DNA adducts have been detected in human lung samples, and increased levels of PAH–DNA adducts in human lung tissue of smokers and ex-smokers relative to non-smokers have been reported in several studies.9 The major adduct formed by activated benzo(a)pyrene, the (+)-anti-benzo(a) pyrene-guanine adduct, is premutagenic, mispairing with A and generating primarily G-to-T transversions. The role of PAHs in lung cancer is consistent with data on mutational analysis of the TP53 gene with the demonstration of a large number of G-to-T transversions at certain bases (hotspots) in this gene in smokers’ lung tumors.12 In vitro studies have shown a direct molecular link between benzo(a)pyrene and the development of lung cancer. Exposure of human epithelial cell cultures to the reactive diol epoxide metabolites of this carcinogen resulted in the formation of adducts and TP53 hotspot mutations, similar to that observed in lung tumors in smokers.13

2 Textbook of Lung Cancer Table 1.1 Carcinogens in cigarette smoke Agent

Amount in mainstream cigarette smoke

IARC evaluation of carcinogenicity In animals

Polynuclear aromatic hydrocarbons Benzo[a]anthracene 20–70 ng Benzo[b]fluoranthene 4–22 ng Benzo[j]fluoranthene 6–21 ng Benzo[k]fluoranthene 6–12 ng Benzo[a]pyrene 8.5–11.6 nga Dibenz[a,h]anthracene 4 ng Dibenzo[a,i]pyrene 1.7–3.2 ng Dibenzo[a,e]pyrene Present Indeno[1,2,3-cd]pyrene 4–20 ng 5-Methylchrysene ND-0.6 ng Heterocyclic hydrocarbons Furan 20–40 µgb Dibenz(a,h)acridine ND–0.1 ng Dibenz(a,j) acridine ND–10 ng Dibenzo(c,g)carbazole ND–0.7 ng Benzo(b)furan Present N-Nitrosamines N-Nitrosodimethylamine 0.1–180 ngb N-Nitrosoethylmethylamine ND–13 ng N-Nitrosodiethylamine ND–25 ngb N-Nitrosopyrrolidine 1.5–110 ngb N-Nitrosopiperidine ND–9 ng N-Nitrosodiethanolamine ND–36 ngb N′-Nitrosonornicotine 154–196 nga 4-(Methylnitrosamino)110–133 nga 1-(3-pyridyl)-1-butanone Aromatic amines 2-Toluidine 30–200 ngb 2,6-Dimethylaniline 4–50 ng 2-Naphthylamine 1–22 ngb 4-Aminobiphenyl 2–5 ngb N-Heterocyclic amines A-α-C 25–260 ng MeA-α-C 2–37 ng IQ 0.3 ng Trp-P-1 0.3–0.5 ng Trp-P-2 0.8–1.1 ng Glu-P-1 0.37–0.89 ng Glu-P-2 0.25–0.88 ng PhIP 11–23 ng

In humans

IARC group

Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient

2A 2B 2B 2B 2A 2A 2B 2B 2B 2B

Sufficient Sufficient Sufficient Sufficient Sufficient

2B 2B 2B 2B 2B

Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient

2A 2B 2A 2B 2B 2B 2Bc 2Bc

Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient

Limited Sufficient Sufficient

2A 2B 1 1 2B 2B 2A 2B 2B 2B 2B 2B (Continued)

Etiology of lung cancer 3

Table 1.1 Continued Agent

Amount in mainstream cigarette smoke

Aldehydes Formaldehyde 10.3–25 µga Acetaldehyde 770–864 µga Phenolic compounds Catechol 59–81 µga Caffeic acid <3 µg Volatile hydrocarbons 1,3-Butadiene 20–40 µgb Isoprene 450–1000 µg Benzene 12–50 µgb Nitrohydrocarbons Nitromethane 0.5–0.6 µg 2-Nitropropane 0.7–1.2 ngc Nitrobenzene 25 µg Miscellaneous organic compounds Acetamide 38–56 µg Acrylamide Present Acrylonitrile 3–15 µg Vinyl chloride 11–15 ng 1,1-Dimethylhydrazine Present Ethylene oxide 7 µg Propylene oxide 0–100 ng Hydrazine 24–43 ng Urethane 20–38 ngb Metals and metal compounds Arsenic 40–120 ngb Beryllium 0.5 ng Nickel ND–600 ng Chromium (hexavalent) 4–70 ng Cadmium 41–62 ngb Cobalt 0.13–0.20 ng Lead (inorganic) 34–85 ng Radio-isotope polonium-210 0.03–1.0 pCi

IARC evaluation of carcinogenicity In animals

In humans

IARC group

Sufficient Sufficient

Limited

2A 2B

Sufficient Sufficient Sufficient Sufficient Sufficient

2B 2B Limited Sufficient

2A 2B 1

Sufficient Sufficient Sufficient

2B 2B 2B

Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient

2B 2A 2B 1 2B 1 2B 2B 2B

Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient Sufficient

Sufficient Limited

Sufficient Sufficient Sufficient Sufficient Sufficient Limited

1 1 1 1 1 2B 2A 1

Modified from Hoffmann and Hoffmann,4 this table shows components of unfiltered mainstream cigarette smoke, with amounts given per cigarette. Virtually all these compounds are known carcinogens in experimental animals. In combination with data on cancer in humans and – in some cases – other relevant data, IARC Monograph classifications for these agents have been established as Group 2B (possibly carcinogenic to humans), Group 2A (probably carcinogenic to humans), or Group 1 (carcinogenic to humans). Abbreviations: ND, not detected; A-α-C, 2-amino-9H-pyrido[2,3-b]indole; IQ, 2-amino-3-methylimidazo-[4,5-b]quinoline; Trp-P-1, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole; Trp-P-2, 3-amino-1-methyl-5H-pyrido[4,3-b]indole; Glu-P-1, 2-amino6-methyl[1,2-a:3′2″-d]imidazole; Glu P-2, 2-aminodipyridol[1,2-a:3′,2″-d]imidazole; PhIP, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine; pCi, picoCurie. a Data from Swauger et al (2002) (for ‘full-flavor’ cigarettes).5 b Data from US Department of Health and Human Services (1989).6 c Corrected value (see Fowler and Bates, 2000).7

4 Textbook of Lung Cancer Table 1.2 Causative agents in cigarette smoke Carcinogens

Major risk factors PAHs Nitroso compounds

Tumor promoters/ co-carcinogens

Catechol Phenol Aldehydes Oxidative radicals

Minor risk factors Polonium-210 Aldehydes Butadiene Ni, Cd, Cr Oxidative radicals

The concentration of nitrosamines found in tobacco products is relatively high, and except for some occupational exposure situations, heavy smokers have the highest exposure to N-nitroso compounds. The socalled tobacco-specific N-nitrosamines (TSNAs), principally the nicotine-derived NNK, are the strongest respiratory carcinogens identified in tobacco products. Adenocarcinoma of the lung is the main type of lung cancer induced by NNK, and both benign and malignant tumors are formed in rats, mice, and hamsters.14 Moreover, human lung tissue metabolically activates NNK, although less effectively than rodent lung tissue. This activation is mediated by P450 monooxygenases, cyclooxygenases, and lipooxygenases. Metabolites of NNK have been reported in urine from smokers, and NNK and N′-nitrosonornicotine (NNN)-specific DNA adducts have been reported at increased levels in the lungs of smokers.8,15 A high frequency of G-to-A transitions in the TP53 gene is consistent with the mutational spectrum expected from NNK.12 NNK might also exert its biologic activity through cell surface receptors such as nicotine acetylcholine receptors (nAchRs) and β-adrenergic receptors.16 Adenocarcinoma has now overtaken squamous cell carcinoma as the most common lung cancer type, consistent with the role of NNK in lung carcinogenesis. NNK concentrations in mainstream smoke have increased while those of benzo(a) pyrene have decreased since the 1960s. There are relatively high levels of metals in cigarette smoke (Figure 1.1). At least 30 metals have been identified.3,4 The contribution of these metals to increased lung cancer risk is poorly understood. Experimental evidence indicates that many metals are effective initiators

of the carcinogenic process, but can also be potential promoters during carcinogenesis. This is particular true for tobacco smoke, where exposure to multiple agents occurs. Cigarette smoke contains a substantial amount of chromium, cadmium, and nickel. It is known that chromium accumulates in the lung and tobacco smoking is the main source of cadmium exposure in humans. It has been reported that chromates are carcinogenic in rats, inducing lung tumors after instillation.17 Cadmium chloride aerosols produce lung adenocarcinoma and squamous cell carcinoma in rats,18 and nickel subsulfide yields lung cancer in rats upon inhalation.19 Because of their relatively high levels in cigarette smoke, these metals may play a role in lung carcinogenesis. They are likely to contribute to lung cancer induction by multiple mechanisms such as inducing DNA damage (single strand breaks, cross-linking of DNA and proteins), and they could potentiate the genotoxicity of other DNAdamaging agents and enhance mutagenesis. Many studies have demonstrated that reactive oxygen species are implicated in metal carcinogenesis. Table 1.2 lists other constituents of tobacco-smoke that could be involved in lung cancer induction. However, less importance has been attributed to these compounds in comparison with PAH and NNK. Inhalation studies of formaldehyde and acetaldehyde have demonstrated that they are respiratory carcinogens in the rat.20 These compounds are weak carcinogens, but the levels are relatively high in cigarette smoke. Polonium-210 (210Po) is a natural constituent of cigarette smoke and will deposit in the lungs of smokers, emitting alpha particles.21 The content of several carcinogens in tobacco has been reduced due to changes in tobacco processing methods and new cigarette filters, but this is not the case with the 210Po concentration, neither in tobacco nor in tobacco smoke. Radiation exposure may induce lung cancer both alone and in interaction with other carcinogens in tobacco. Animal studies have shown that 210Po is a strong pulmonary carcinogen in rats and Syrian golden hamsters.22 Cigarette smoke contains large amounts of free radicals and is known to induce oxidative damage. Both gas and particulate phases are highly oxidized, and damage the lung. Alkenes (i.e. unsaturated aliphatic hydrocarbons), nitrosamines, aromatic and heterocyclic hydrocarbons, amines, and catechol and hydroquinone are all well known sources of reactive oxygen species such as hydroxyl radicals, superoxides, and peroxides.23 Damage can also result from the activation of phagocytic cells that generate reactive oxygen species (ROS).24 Cigarette smoke is a strong inflammatory stimulus that induces

Etiology of lung cancer 5 Causative agents in cigarette smoke: PAH, NNK, 210Po, Cr, Cd, Ni, aldehydes, oxidative radicals Phase 1 (activation) Susceptibility: Variation in metabolism and DNA repair Nutrition Immunologic status

P 450

DNA-damaging metabolites

Chronic exposure

DNA repair Days

DNA repair 10–30 years

Excretion

Synergistic effect: Asbestos Chloromethyl ethers Mustard gas Radioactive ore

Preneoplastic cells

Initiated cells

Normal cells

Phase 2 (detoxification)

Progression

Lung cancer

DNA repair Months

Genetic changes: TP53, KRAS, EGFR, inactivation of FHIT/RASSF1/SEMA3B (3p), INK4, RB Activation of CCDN1; MYC1 - amplification LOH (2q, 5q, 9q, 18q, 22q)

Figure 1.1 Lung carcinogenesis.

proinflammatory cytokines and recruits activated macrophages and neutrophils to lung tissue.25 Neutrophils play an important role in the defense of the lung through a variety of activities and generate oxidative radicals when exposed to PAHs and aromatic amines. The oxidative capacity of neutrophils is therefore important as a potential cause of oxidative damage to the lung. Several epidemiologic studies have associated lung inflammatory diseases such as asthma, bronchitis, and chronic obstructive pulmonary disease (COPD) with an increased risk of lung cancer development. DNA is an important target for ROS. In order for ROS to induce DNA damage, a sufficient concentration must be available to overwhelm the antioxidant capacity of the lung. Products that result from oxidative damage to both lipids and DNA have been detected in smokers at higher levels than in non-smokers. Although the direct role of such products in carcinogenesis is unclear, 8-oxoguanine (8-oxo-G), a frequent product of oxidative damage, has miscoding properties associated with the cancer induction process.26 Studies indicate that unrepaired 8-oxo-G gives rise to G-to-T transversions. The most abundant genetic change induced as a consequence of oxidative damage is GC-to-AT transition. Apart from oxidative modification of DNA bases, free radicals are also able to induce single strand breaks.

Nicotine is the agent in tobacco capable of producing addiction, or nicotine dependence, and exists at high concentrations in the blood of smokers. Direct involvement of nicotine in the development of lung cancer has not yet been shown, but nicotine does appear to play an important role and may have multiple sites of action. It is absorbed rapidly when smokers inhale. Specific, high-affinity nAChRs are found on human lung cancer cells of all histologic types as well as in normal lung tissue.27 Chronic exposure to nicotine can lead to the activation of growth-promoting pathways upon its interaction with nAChRs, and may also affect apoptosis and angiogenesis.28

ENVIRONMENTAL TOBACCO SMOKE Environmental tobacco smoke (ETS), or passive smoking, is a mixture of exhaled mainstream smoke and sidestream smoke diluted with ambient air. Cigarettes generate a large amount of ETS and affected individuals are exposed to the same carcinogens as an active smoker. However, the relative proportions of the particular compounds may differ between mainstream and sidestream smoke. For example, due to filters, concentrations of PAHs such as benzo(a)pyrene and benzo(a) anthracene in the sidestream are approximately 10-fold

6 Textbook of Lung Cancer

higher than those in mainstream smoke. Benzene, formaldehyde, hydrazine, butadiene, N-nitrosamines, aniline, 2-naphthylamine, and 4-aminobiphenyl may also be present at higher concentrations in sidestream smoke.29 Many epidemiologic studies, which were evaluated by the IARC in 2004,3 have shown an increased lung cancer risk in never-smokers exposed to ETS. This is particularly true for spouses of active smokers, where ETS-exposed never-smoking females and males have an excess risk of lung cancer in the order of 20 or 30%, respectively. Never-smokers exposed to ETS in the workplace may also be at an increased risk (12–19%). Experimental studies have confirmed the carcinogenic potential of ETS. Thus, concentrations of tobaccosmoke-related compounds adducted to biologic macromolecules such as proteins, and to a lesser extent DNA, have been found to be increased in individuals exposed to ETS.3 Also, lung tumors from ETS-exposed nonsmoking individuals show TP53 and KRAS mutations similar to those found in tumors from smokers, although at a lower frequency.30,31

AIR POLLUTION, RADON, WORKPLACE EXPOSURE, AND VIRUSES The different incidence rates for lung cancer among non-smokers in different countries suggest that environmental agents can modify the risk. Air pollution is a complex mixture of different gaseous and particulate components that may pose a moderate risk factor for lung cancer. Numerous air pollutants resulting from heavy traffic, burning of fossil fuels, and industrial plants are potential contributors to the incidence of lung cancer. These include PAH, formaldehyde, benzene, ethylene oxide, petroleum vapors, and metals. An association between lung cancer and air pollution has been reported in studies from cities. Urban residents with the highest exposure levels seem to have an increase in lung cancer in the range of 1.5 times that of rural residents.32 In a large European prospective study, it was found that residence in proximity to heavy-traffic roads or exposure to NO2 concentrations greater than 30 µg/m3 can increase the risk of lung cancer.33 In the case of NO2, the lung cancer risk ratio has shown an exposure–response relationship.34 In other studies, particulate matter (fine particles), SO2, and black smoke have all been associated with a moderate increase in the risk of lung cancer. However, analysis is complicated due to the fact that air pollution is a complex mixture,

with numerous air pollutants that vary during the year and over time. Since the lung has a large respiratory volume (500–600 liters of air/h) with a large surface area (75–85 m2), and a large blood perfusion, exposure to toxic compounds in the ambient air could lead to lung toxicity and lung cancer development even at low levels. Radon, a naturally reactive but chemically inert gas found ubiquitously in the environment, emanates as a toxic gas from the soil and from building material of terrestrial origin, such as stone, bricks, and concrete. High levels of radon exposure occur in occupational settings, particularly in uranium mines. People are also subjected to residential radon exposure, which may be increasing due to the tendency to reduce ventilation rates in indoor air. The carcinogenicity of radon is attributable mainly to its short-lived, radioactive, alphaemitting daughters, polonium-214 and polonium-218.35 In miners, increasing risk of lung cancer is associated with increasing cumulative exposure to radon.36 There is also compelling evidence that indoor radon is an important contributor to the risk of lung cancer.37 The dose–response relation between residential radon exposure and excess risk of lung cancer appears to be linear with no threshold. Overall estimates have been made that radon may contribute to 9% of all lung cancers, and the available data suggest that the risks of lung cancer from exposure to radon and smoking are at least additive. Workplace exposure plays an important role in the causation of lung cancer. The evidence for lung cancer induction by occupational exposure to metals such as beryllium, chromium, nickel and arsenic is convincing and well documented.38 High exposure to PAH occurs in several occupations, such as those involved in aluminium production, coke production, and coal gasification, iron and steel workers, bus drivers (because of diesel engine exhaust), roofers, and asphalt workers. The lung is the major target organ among PAH-exposed workers.39 Although occupational exposure to asbestos is no longer an issue in most developed countries, in several developing countries exposure is widespread and may be a significant etiologic factor for lung cancer. As in most other exposure scenarios, tobacco smoking is the main cause of lung cancer in asbestos-exposed workers, and the relative risk seems to be higher among non-smokers compared to smokers.40 Crystalline silica, which may be inhaled in occupational settings, has been classified as a lung carcinogen, with an apparent linear dose–response relationship without any threshold.41 It is important to note, however, when assessing the

Etiology of lung cancer 7

etiology of lung cancer associated with occupational exposure, that a significant confounder to be considered is tobacco smoking. Oncogenic viruses may be involved in the etiology of lung cancer. Some evidence has been provided for the involvement of human papilloma viruses, but detection rates of the viruses in bronchial carcinomas are highly variable, ranging from 0 to 100% in different studies.42 Regarding other oncogenic viruses such as Epstein– Barr virus, human cytomegalovirus, human herpes virus-8, and simian virus 40, the evidence is scarce.43

repair genes involved in different repair pathways show associations. There is increasing knowledge of the genetic defects that give rise to the observed variation in, and, more importantly functional significance of these allelic variants. However, there are numerous conflicting reports on the association between different polymorphisms and lung cancer risk. Larger studies are needed in this area.

FEMALES AND LUNG CANCER SUSCEPTIBILITY GENETIC SUSCEPTIBILITY AND LUNG CANCER ETIOLOGY Host factors may influence individual susceptibility to tobacco smoke. This may be illustrated by the fact that only 1 in 10 lifetime smokers will develop lung cancer. Several epidemiologic studies have indicated that there are genetic factors modifying the risk of individuals to lung cancer. Some degree of familial aggregation of lung cancer is evident in most family studies. One study has reported linkage to chromosome 6q in lung cancer families, strongly supporting the existence of a gene for lung cancer.44 The human genome project has resulted in increasing information becoming available on the existence of polymorphisms in human genes. Susceptibility to lung cancer may be modulated by host-specific factors including differences in carcinogen metabolism and detoxification, DNA repair, cell cycle control, cell signaling, apoptosis, and inflammation pathways. Several studies have been designed to evaluate a large number of sequence variants among multiple genes of drug-metabolizing enzymes.45 Procarcinogens in tobacco smoke are activated by several forms of cytochrome P450 (phase I) and detoxified by glutathione S-transferase (GST), NADPH:quinone oxidoreductase (NQO), N-acetyl-transferase (NAT), and others (phase II). Many of these genes exhibit allelism and there is accumulating evidence that some CYP, GST, NQO, and NAT genotypes are associated with an altered risk of lung cancer. The removal and repair of DNA damage plays a key role in protecting the integrity of the genome from the insults of genotoxic agents such as PAH and NNK found in tobacco smoke. Lung cancer patients were reported to have a lower DNA repair capacity, and recent studies have assessed the relationship between single nucleotide polymorphisms (SNPs) in several DNA repair genes and the risk of lung cancer.45–47 Several DNA

The relative lung cancer burden from women is increasing, partly due to their changing smoking habits. Although controversial, the increase in lung cancer among females is possibly also partly due to a higher susceptibility to tobacco smoke carcinogens. Several studies have reported the relative risk of lung cancer among females to exceed that of males by a factor of 1.5 to 2.5.48–50 Although not all epidemiologic studies have been able to confirm that females are at increased risk,51,52 it is clear that biologic factors involved in lung cancer development differ between the sexes. Experimental studies have indicated sex differences in PAH metabolism, DNA repair capacity, and cell proliferation potential that may support this hypothesis. By analyzing the TP53 gene mutational spectra in a large number of lung cancer cases, G:C-to-T:A hotspot mutations were found at a higher frequency among female smokers compared to female never-smokers. Similar differences were not found among males.53 Since G:C-to-T:A transversions are associated with exposure to PAH, this indicates a specific role for PAH in generating this particular signature mutation in women. Women have also been reported to have increased levels of pulmonary tobacco-smoke-induced DNA damage in the form of PAH-related adducts.54 The DNA-adduct level may be a predictor of cancer risk.55 Higher DNA-adduct levels among females coincide with a higher level of expression of the smoking-induced cytochrome P450 1A1 (CYP1A1), which is an important gene in the metabolic activation of PAH.56 Estrogens and their receptors have been hypothesized to be involved in these sex differences by interfering with the transcription-activating activity of the aryl hydrocarbon receptor (AHR). AHR is a ligand-activated transcription factor with high affinity for PAH. In studies with lymphocytes isolated from lung cancer patients, it was found that females might also have a lower capacity to

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repair DNA damage,57 which may result in increased susceptibility to the manifestation of mutations. One report has indicated that pulmonary expression of the gastrin-releasing peptide receptor (GRPR), which is involved in lung development during fetal stages, is more frequent among women than men.58 The GRPR gene is induced by smoking and is located on a region of the X-chromosome that appears to escape X-chromosome inactivation in females. Activation of the GRPR has been associated with an increased proliferative response in human airway epithelial cells. Thus, this represents a model where smoking may induce the gene to a higher extent among women. In summary, tobacco smoking (active smoking or exposure to environmental tobacco smoke) plays a major etiologic role in lung carcinogenesis. More than 60 compounds in tobacco smoke have been identified as carcinogenic. Other etiologic factors of minor, but still significant importance for the disease are air pollution, radon, workplace exposure, and viruses. Genetic differences in susceptibility to lung cancer are apparent and sex differences may be involved. REFERENCES 1. World Cancer Research Fund, American Institute for Cancer Research. Food, nutrition and the prevention of cancer: a global perspective. Washington, DC: American Institute for Cancer Research, 1997: 37–145. 2. Parkin DM, Pisani P, Lopez AD, Masuyer E. At least one in seven cases of cancer is caused by smoking: global estimates for 1985. Int J Cancer 1994; 59: 494–504. 3. International Agency for Research on Cancer. Tobacco smoke and involuntary smoking. IARC Monogr Eval Carcin Risk Hum 2004; 83. 4. Hoffmann D, Hoffmann I. The changing cigarette, 1950–1995. J Toxicol Environ Health 1997; 50: 307–64. 5. Swauger JE, Steichen TJ, Murphy PA et al. An analysis of the mainstream smoke chemistry of samples of the US cigarette market acquired between 1995 and 2000. Regul Toxicol Pharmacol 2002; 35: 142–56. 6. US Department of Health and Human Services (DHHS). Reducing the health consequences of smoking: 25 years of progress. A report of the surgeon general, Washington DC: US government printing office, 1989. 7. Fowler J, Bates M. The chemical constituents in cigarettes and cigarette smoke. Priorities for harm reduction. Report to the New Zealand Ministry of Health. Epidemiology and Toxicology group, Porirua, ESR, Kenepura Science Centre. 8. Hecht SS. Cigarette smoking and lung cancer: chemical mechanisms and approaches to prevention. Lancet Oncol 2002; 3: 461–9. 9. Phillips DH. Smoking-related DNA and protein adducts in human tissues. Carcinogenesis 2002; 23: 1979–2004.

10. Phillips DH. DNA adducts as markers of exposure and risk. Mutat Res 2005; 577: 284–92. 11. Vineis P, Perera F. DNA adducts as markers of exposure to carcinogens and risk of cancer. Int J Cancer 2000; 88: 325–8. 12. Calvez FL, Mukeria A, Hunt JD et al. TP53 and KRAS mutation load and types in lung cancers in relation to tobacco smoke: distinct patterns in never, former, and current smokers. Cancer Res 2005; 65: 5076–83. 13. Denissenko MF, Pao A, Tang M, Pfeifer GP. Preferential formation of benzo[a]pyrene adducts at lung cancer mutational hotspots in p53. Science 1996; 274: 430–2. 14. Hecht SS, Carmella SG, Foiles PG et al. Tobacco-specific nitrosamine adducts: studies in laboratory animals and humans. Environ Health Perspect 1993; 99: 57–63. 15. Hecth SS. Human urinary carcinogen metabolites: biomarkers for investigating tobacco and cancer. Carcinogenesis 2002; 23: 907–22. 16. Schuller HM. Mechanisms of smoking-related lung and pancreatic adenocarcinoma development. Nat Cancer Rev 2002; 2: 455–63. 17. Costa M. Toxicity and carcinogenicity of Cr (VI) in animal models and humans. Crit Rev Toxicol 1997; 27: 431–42. 18. Waalkes MP. Cadmium carcinogenesis. Mutat Res 2003; 533: 107–20. 19. Oller AR, Costa M, Oberdorster G. Carcinogenicity assessment of selected nickel compounds. Toxicol Appl Pharmacol 1997; 143: 152–66. 20. International Agency for Research on Cancer. Formaldehyde. IARC Monogr Eval Carcin Risk Hum 1982; 4: 131–2. 21. Khater AEM. Polonium-210 budget in cigarettes. J Environ Radioactivity 2004; 71: 33–41. 22. Little JB, Kennedy AR, McCandy RB. Effect of dose rate on the induction of experimental lung cancer in hamsters by alpha radiation. Radiat Res 1985; 103: 293–9. 23. Rahman I. Oxidative stress, chromatin remodelling and gene transcription in inflammation and chronic lung disease. Biochem Mol Biol 2003; 36: 95–109. 24. Coussens LM, Werb Z. Inflammation and cancer. Nature 2002; 420: 860–7. 25. Hunninghake GW, Crystal RG. Cigarette smoking and lung destruction: accumulation of neutrophils in the lungs of cigarette smokers. Am Rev Respir Dis 1990; 128: 833–8. 26. Kasai H. Analysis of a form of oxidative DNA-damage, 8-hydroxy-2′-deoxyguanosine, as a marker of cellular oxidative stress during carcinogenesis. Mutat Res 1997; 387: 147–63. 27. Maneckjee R, Minna JD. Opioid and nicotine receptors affect growth regulation of human lung cancer cell lines. Proc Natl Acad Sci USA 1990; 87: 3294–8. 28. Xin M, Deng X. Nicotine inactivation of the propoptotic function of Bax through phosphorylation. J Biol Chem 2005; 280: 10781–9. 29. Dockery DW, Trichopoulos D. Risk of lung cancer from environmental exposures to tobacco smoke. Cancer Causes Control 1997; 8: 333–45. 30. Husgafvel-Pursiainen K, Boffetta P, Kannio A. p53 mutations and exposure to environmental tobacco smoke in a multicenter study on lung cancer. Cancer Res 2000; 60: 2906–11. 31. Vahakangas KH, Bennett WP, Castren K et al. p53 and K-ras mutations in lung cancers from former and never-smoking women. Cancer Res 2001; 61: 4350–6.

Etiology of lung cancer 9 32. Boffetta P. Epidemiology of environmental and occupational cancer. Oncogene 2004; 23: 6392–403. 33. Vineis P, Hoek G, Krzyzanowski M et al. Air pollution and risk of lung cancer in a prospective study in Europe. Int J Cancer 2006; 119: 164–74. 34. Nafstad P, Haheim LL, Oftedal B et al. Lung cancer and air pollution: a 27 year follow up of 16209 Norwegian men. Thorax 2003; 58: 1071–6. 35. Phillips PS, Denman AR. Radon: a human carcinogen. Sci Prog 1997; 80: 317–36. 36. International Agency for Research on Cancer. Ionizing radiation, part 2: some internally deposited radionuclides. IARC Monogr Eval Carcin Risk Hum 2001; 78: 137–66. 37. Darby S, Hill D, Auvinen A, Barros-Dios JM et al. Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies. BMJ 2005; 330: 223. 38. Siemiatycki J, Richardson L, Straif K et al. Listing occupational carcinogens. Environ Health Perspect 2004; 112: 1447–59. 39. Boffetta P, Jourenkova N, Gustafsson P. Cancer risk from occupational exposure to polycyclic aromatic hydrocarbons. Cancer Causes Control 1997; 8: 444–72. 40. Liddell FDK. The interaction of asbestos and smoking in lung cancer. Ann Occup Hyg 2001; 45: 341–56. 41. Steenland K, Mannetje A, Boffetta P et al. Pooled exposure– response analysis and risk assessment for lung cancer in 10 cohorts of silica-exposed workers: an IARC multicentre study. Cancer Causes Control 2001; 12: 773–84. 42. Syrjanen KJ. HPV infections and lung cancer. J Clin Pathol 2002; 55: 885–91. 43. Brouchet L, Valmary S, Dahan M. Detection of oncogenic virus genomes and gene products in lung carcinoma. Br J Cancer 2005; 92: 743–6. 44. Bailey-Wilson JE, Amos CI, Pinney SM et al. A major lung cancer susceptibility locus maps to chromosome 6q23–25. Am J Hum Genet 2004; 75: 460–74. 45. Liu G, Zhou W, Christiani DC. Molecular epidemiology of non-small cell lung cancer. Semin Respir Crit Care Med 2005; 26: 265–72. 46. Wei Q, Cheng L, Hong WK, Spitz MR. Reduced DNA repair capacity in lung cancer patients. Cancer Res 1996; 56: 4103–7.

47. Zienolddiny S, Campa D, Lind H et al. Polymorphisms of DNA repair genes and risk of non-small cell lung cancer. Carcinogenesis 2006; 27: 560–7. 48. Risch HA, Howe GR, Jain M et al. Are female smokers at higher risk for lung cancer than male smokers? A case-control analysis by histologic type. Am J Epidemiol 1993; 138: 281–93. 49. Zang EA, Wynder EL. Differences in lung cancer risk between men and women: examination of the evidence. J Natl Cancer Inst 1996; 88: 183–92. 50. Henschke CI, Miettinen OS. Women’s susceptibility to tobacco carcinogens. Lung Cancer 2004; 43: 1–5. 51. Kreuzer M, Boffetta P, Whitley E et al. Gender differences in lung cancer risk by smoking: a multicentre case-control study in Germany and Italy. Br J Cancer 2000; 82: 227–33. 52. Bain C, Feskanich D, Speizer FE et al. Lung cancer rates in men and women with comparable histories of smoking. J Natl Cancer Inst 2004; 96: 826–34. 53. Toyooka S, Tsuda T, Gazdar AF. The TP53 gene, tobacco exposure, and lung cancer. Hum Mutat 2003; 21: 229–39. 54. Mollerup S, Ryberg D, Hewer A et al. Sex differences in lung CYP1A1 expression and DNA adduct levels among lung cancer patients. Cancer Res 1999; 59: 3317–20. 55. Veglia F, Matullo G, Vineis P. Bulky DNA adducts and risk of cancer: a meta-analysis. Cancer Epidemiol Biomarkers Prev 2003; 12: 157–60. 56. Mollerup S, Berge G, Bæra R et al. Sex differences in risk of lung cancer: expression of genes in the PAH bioactivation pathway in relation to smoking and bulky DNA adducts. Int J Cancer 2006; 119: 141–4. 57. Wei Q, Cheng L, Amos CI et al. Repair of tobacco carcinogen-induced DNA adducts and lung cancer risk: a molecular epidemiology study. J Natl Cancer Inst 2000; 92: 1764–72. 58. Shriver SP, Bourdeau HA, Gubish CT et al. Sex-specific expression of gastrin-releasing peptide receptor: relationship to smoking history and risk of lung cancer. J Natl Cancer Inst 2000; 92: 24–33.

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Epidemiology of lung cancer: a century of great success and ignominious failure Peter Boyle, Sara Gandini, Nigel Gray Contents Introduction • Phase I: public health success, 1930s onwards • Phase II: understanding etiology, losing ground in incidence and mortality • Phase III: descriptive epidemiology of lung cancer • Phase IV: public health failure, 1960s onwards

INTRODUCTION The present century has witnessed a remarkable epidemic of lung cancer. The words of Adler,1 published in 1912, today make salutary reading: Is it worthwhile to write a monograph on the subject of primary malignant tumours of the lung? In the course of the last two centuries an ever-increasing literature has accumulated around this subject. But this literature is without correlation, much of it buried in dissertations and other out-of-the-way places, and, with but a few notable exceptions, no attempt has been made to study the subject as a whole, either the pathological or the clinical aspect having been emphasised at the expense of the other, according to the special predilection of the author. On one point, however, there is nearly complete consensus of opinion, and that is that primary malignant neoplasms of the lungs are among the rarest forms of the disease. This latter opinion of the extreme rarity of primary tumours has persisted for centuries. Lung cancer is currently the most common form of cancer worldwide. It is the most common cause of cancer death in men in North America and in virtually all European countries, west and east, and it is increasingly common as a cause of death in developing populations in Asia, Latin America, and Africa, although comparable high-quality data are not available from many of these populations. From being virtually an unknown and rare disease at the beginning of the last century, public health has documented the development of a true epidemic of lung cancer through the 20th century, and has failed to alleviate the situation by positive actions. Knowing the cause, which has been the case for

lung cancer since at least the middle of the last century, has been of little value in public health terms, since there has been no real action taken to reduce the impact of this serious disease. In viewing the century of lung cancer epidemiology, there are a number of distinct phases that can be identified. Initially (phase I), there was the great success of epidemiology, the basic science of public health, in establishing the causal link between cigarette smoking and lung cancer risk. Following this period, from the mid1950s onwards, there was a period (phase II) where there was an increasing understanding of the etiology of lung cancer, and simultaneously public health began losing ground as smoking rates led to great increases in the incidence and mortality of the disease, particularly among men in developed countries. The association between tobacco smoking and lung cancer became widely known, and many groups actively took up the movement towards tobacco control. During this period (phase III), the situation stabilized while activists and scientists united to try to bring the adverse effects of tobacco smoking to general attention and thereby to take actions designed to reduce smoking and its harmful side-effects. It quickly became clear that a great deal of ground had been lost, and during phase IV large increases in lung cancer among women became apparent, indicating the great failure of public health to curb the development of the habit among women.

PHASE I: PUBLIC HEALTH SUCCESS, 1930s ONWARDS The association between tobacco smoking and the development of lung cancer appears to have been suggested in the UK in 1927.2 The first interview study on tobacco smoking and lung cancer seems to have been reported from Vienna,3 where lung cancer rates

Epidemiology of lung cancer: a century of great success and ignominious failure 11

had risen dramatically. Fleckseder3 found 51 smokers among 54 patients with lung cancer. Thirty-seven of these smoked between 20 and 90 cigarettes daily, while excessive smoking of pipes, cigars, or both was rarer. The same association was alluded to in a report from the USA4 on a study primarily of a series of 79 patients treated by total pneumonectomy. A report from Cologne followed one year later,5 based on the postmortem records of 96 patients. The patients (or more usually the relatives of fatal cases) were interviewed as to patient’s occupation, tobacco consumption, and exposure to specific ‘inhalants’. Reanalysis of Muller’s5 data shows a relative risk of 3.1 among moderate smokers, 2.7 among heavy smokers, 16.8 among very heavy smokers, and 29.16 among excessive smokers. Within the limitations of the study (e.g. small numbers, especially among non-smoking cases, and possible inaccuracies in elucidation of precise smoking histories), these results were noticeably similar to results obtained from later case–control studies in the USA and, apart from a lack of increase among heavy smokers, there is the possible appearance of a dose–response relationship. A study of smoking habits and occupation based on 195 postmortem records of lung cancer cases from the Pathology Institute at Jena for the years 1930–1941 was reported: usable replies were obtained from relatives of 93 men and 16 women. Of the women, 13 were nonsmokers.6 The authors attempted to collect control information by interviewing 700 men in Jena between the ages of 53 and 54, the average age of the lung cancer patients at death (53.9 years). This was a study performed in Germany towards the end of the Second World War, and only 270 men from Jena responded to the questionnaire. The authors showed great insight in concluding that wartime conditions (particularly the rationing system) may have favored results from non-smokers. They reported a statistically significant difference between non-smokers and heavy smokers among lung cancer patients on the one hand and normal patients on the other. Realizing the possible errors on their material, they concluded that there was a considerable probability that lung cancer was far more frequent among non-smokers than expected. Their data are such that an approximate relative risk can be calculated: the risk relative to non-smokers was 1.90 among light smokers, 9.05 among moderate smokers, and 11.34 among heavy/excessive smokers. Again there appears to be a moderate dose–response relationship. The rapid escalation in lung cancer during the 1940s reached a level that permitted more and larger studies

to be conducted and, in 1950, five major contributions were made to the literature.7–11 The data presented by Wynder and Graham10 are capable of transformation to calculate the relative risks (the concept of which was unknown for a few more years). Setting the risk among non-smokers at 1.0, there is to some extent or other a dose–response relationship with increasing levels of smoking in all age groups. Together with the study of Wynder and Graham,10 the fifth paper published on this subject during the year represented a significant contribution not only to knowledge about smoking and cancer but also to the methodology of retrospective epidemiologic studies.11 This well-planned, controlled, and well-conducted study was initially reported,11 and completed and published more extensively two years later. It is this latter report12 that we shall discuss here. Doll and Hill12 did not discuss cigar smoking, but calculated that use of one ounce of pipe tobacco was the equivalent of 26.5 cigarettes, and one ounce per week was equivalent to smoking four cigarettes per day. Non-smokers were defined as people who had never consistently smoked as much as one cigarette per day for as long as one year.11 The strongest difference between cases and controls (for both males and females) was found to be the average amount smoked daily over the 10 years preceding the patient’s illness. Qualitatively similar results were also obtained using the amount smoked immediately before the patient’s illness, the maximum amount ever smoked regularly, the total smoked since smoking began, and the average amount smoked daily over the 10 years preceding the patient’s illness, over the penultimate 10 years and over the whole of the patient’s life since the age of 15 (even after allowance had been made for recorded changes in smoking habit). Patients who recognized that they inhaled were found no more frequently in the lung cancer group than in the control group, although those cases with growths of central origin inhaled less frequently than normal. It also appeared that lung cancer patients more frequently had a history of preceding pneumonia or chronic bronchitis, while other respiratory illnesses were referred to with approximately equal frequency by the two groups. Doll and Hill’s reports11,12 contained a remarkable amount of information, but the fundamental finding in men was a highly significant difference between the proportions of non-smokers and of smokers in the disease group and in the control group. A less marked series of differences was reported for women. Highly

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significant differences were also shown between the proportions of both groups smoking different average amounts, i.e. between heavy and light smokers, and this result held for males and females. It is apparent from the raw data that there is a dose–response relationship present. Less marked but nevertheless distinct differences were found when the duration of smoking was considered rather than the amount smoked. Lung cancer cases, as a group, began to smoke earlier; they continued to smoke longer and gave up less often and, when they did, did so for shorter periods. In males, all these differences were statistically significant, but, although the differences were in the same direction in women, they did not reach the commonly accepted (5%) level of statistical significance. These five studies,7–11 but mainly the impact of two,10,11 alerted the medical and scientific community to the serious health hazards associated with cigarette smoking. Once alerted, the public response to these studies was a significant, but brief, drop in the per capita consumption of cigarettes in both the USA and the UK.

PHASE II: UNDERSTANDING ETIOLOGY, LOSING GROUND IN INCIDENCE AND MORTALITY Throughout the 1950s, a mass of information was published demonstrating the association between lung cancer and cigarette smoking, using data derived from retrospective studies. Many concentrated on inhalation and, while some studies demonstrated a higher occurrence of inhalation among lung cancer patients than among controls, others failed to detect this association. The US Surgeon General was moved by the weight of evidence associating smoking with cancer of the lung, as well as of other sites, to produce an official statement on ‘Smoking and Health’ on behalf of the US Government.13 This created a worldwide reaction, since it implicated a frightening link between cigarette smoking and a variety of fatal diseases in a document of impeccable scientific authority. This report weighed the available evidence, and considered that it had been established that cigarette smoking was causally related to lung cancer in men, and judged cigarette smoking in the USA a sufficiently important health hazard to warrant remedial action. In the 15 years that passed from that initial report, the body of evidence increased, and extended to include

women,14 in whom lung cancer had increased fivefold in two decades in the USA. The Secretary for Health of the time (Mr Joseph Califano) concluded ‘that smoking is the largest preventable cause of death in America’. An important factor in the causal relationship between smoking and lung cancer is the demonstrated dose– response relationship. In epidemiologic studies, the dose has been measured by: • • • • • • • • •

the number of cigarettes smoked per day at interview; the maximum number of cigarettes smoked per day; the age when smoking commenced; the degree of inhalation of tobacco smoke; the total number of years smoked; the total lifetime number of cigarettes smoked; the tar and nicotine levels of the brand of cigarettes used; the number of puffs per cigarette; the length of the unburned portion of cigarette.

A variety of combinations of these variables can be converted into dosage scores. Lung cancer mortality ratios exhibit an inverse relationship with the age of initiation of the smoking habit. Those who develop the habit at school have a much higher risk of lung cancer than those who begin smoking at age 25+, in whom the risk is only four to five times that of non-smokers. Available data show a strong dose–response relationship between self-reported inhalation of cigarette smoke and lung cancer mortality. Those who inhale deeply have risks double those of smokers who do not. The American Cancer Society 25 State Study15 reported a mortality ratio among non-smokers of 1.0, a mortality ratio of 8.0 among smokers who stated that they did not inhale, and elevations in this risk among those who inhaled slightly (8.9), moderately (13.1) and deeply (17.0). Similar results were reported from a Swedish study:16 although the mortality ratios among nonsmokers (1.0), non-inhalers (3.7), light inhalers (7.8), and deep inhalers (9.2) were smaller in magnitude, the same steady pattern was found. Although it has been suggested for some time that the risk of developing lung cancer increases with the tar and nicotine content of cigarettes there has not been any substantial evidence to suggest that individuals who switch to lower-tar and lower-nicotine cigarettes experience less lung cancer mortality.17 It has been proposed that, if the tar and nicotine contents of tobacco

Epidemiology of lung cancer: a century of great success and ignominious failure 13

were reduced, smokers might increase the number of cigarettes smoked per day and effectively vitiate any benefit. On the other hand, those who switch to low-tar and low-nicotine brands might inhale smoke more deeply than smokers of high-tar and high-nicotine cigarettes, and thus exposure to tar and nicotine might be reduced. The relationship of tar and nicotine was carefully examined with respect to lung cancer in a major study,18 in which 897 825 men and women were classified by levels of tar and nicotine smoked. Brands were considered to be high in nicotine if they contained between 2.0 and 2.7 mg of nicotine and high in tar if they contained between 25.8 and 35.7 mg of tar. The medium levels of tar and nicotine were set at 17.6 and 25.7 mg and at 1.2 and 1.9 mg, respectively. Low tar and nicotine levels were all those below these limits. The risk in the high-tar and high-nicotine group of makes was set at 1.0, and the relative risks in the medium group (risk ratio, RR = 0.95) and low group (RR = 0.81) were appreciably lower. Similar results were found for females: high (RR = 1.0), medium (RR = 0.79), and low (RR = 0.60). These results take into account the daily cigarette consumption. In other words, for men smoking the same number of cigarettes per day, there appears to be an almost 20% reduction in the risk of developing lung cancer with the use of cigarettes low in tar and nicotine. In females, keeping the number of cigarettes smoked per day constant, there appears to be a 40% reduction in risk. The amount of tar and nicotine taken into the body per day obviously depends on the number of cigarettes smoked as well as on the tar and nicotine content of individual cigarettes. Hammond therefore performed a second analysis comparing subjects who smoked 1–19 high-tar and -nicotine cigarettes per day with those who smoked 20–39 low-tar and -nicotine cigarettes per day. Setting the risk to be 1.0 among the high categories of both males and females, Hammond found risks of 1.6 (males) and 2.1 (females) among the groups who smoked 20–39 low-tar and -nicotine cigarettes. He concluded that the number of cigarettes smoked per day was relatively more important than the tar and nicotine content.15,18 All these early observations were regarding forms of cancer and forms of tobacco smoking that were the most common at the period. Cigarette smoking increased heavily in Europe during the last years of Napoleon,19 and the habit spread during the Crimean War, accelerated around 1900 and reached many men, and increasingly women, during the First World War

(1914–1918). In many countries, such as the USA and the UK, women began to reach the same smoking levels as men during the Second World War (1939–1945). Subsequent to this period, cancer was becoming more frequent, and was developing into an international disease that was to become, by the latter part of the 20th century, a significant global public health problem. An increasing number of forms of cancer became linked with cigarette smoking: initially oral cancers, then lung cancer, bladder cancer, laryngeal cancer, esophageal cancer, pancreatic cancer, acute myeloid leukemia, cervical cancer, kidney cancer, and gastric cancer. Several of these are of unusually high frequency in international populations.20

PHASE III: DESCRIPTIVE EPIDEMIOLOGY OF LUNG CANCER The main tobacco-related site is the lung. Lung cancer rates in self-reported non-smokers from various studies are of the order of only 10–15 per 100 000. The IARC monograph Tobacco Smoking21 gave estimates of the proportions of lung cancer deaths attributable to tobacco smoking in five developed countries (Canada, England and Wales, Japan, Sweden, and the USA): these ranged between 83% and 92% for males, and between 57% and 80% for females. The most recent, international, cancer incidence data are available for the period around 1990. The highest incidence rate in men is recorded among the AfroAmerican population of New Orleans in the USA, where the average, annual, age-standardized rate per 100 000 person-years is 110.8 (Table 2.1). Other Afro-American populations in the USA also have remarkably high lung cancer rates in men. Rates are also high among the Maori population of New Zealand, where the incidence rate is 99.7 per 100 000 (Table 2.1). The incidence rate is high in Lower Silesia (Poland) and in the west of Scotland (Table 2.1). There are virtually no regions of the world where the annual incidence rates are low: the lowest incidence rates are reported from a variety of population groups from the developing world (Table 2.2). Among women, the highest rates are found in the Maori population group of New Zealand (72.9 per 100 000) (Table 2.3). High rates are also found among a variety of populations of North America – both AfroAmerican and Caucasian. Notably high rates are reported from the west of Scotland, where incidence rates are high in men as well as in women (Table 2.3).

14 Textbook of Lung Cancer Table 2.1 Highest incidence rates of cancer of the trachea, bronchus and lung in men circa 1990 Registry

Cases

ASRa

USA, New Orleans: Black (1988–1992) USA, Central Louisiana: Black (1988–1992) USA, Detroit: Black (1988–1992) USA, San Francisco: Black (1988–1992) New Zealand: Maori (1988–1992) USA, SEER:b Black (1988–1992) USA, Atlanta: Black (1988–1992) Poland, Lower Silesia (1988–1992) Canada, Northwest Territories (1983–1992) UK, Scotland, west (1988–1992) USA, Los Angeles: Black (1988–1992) USA, Connecticut: Black (1988–1992) Italy, Ferrara (1991–1992) USA, New Orleans: White (1988–1992) Italy, Trieste (1989–1992)

842 172 2263 1003 387 4964 892 7213 126 8877 1925 422 597 1707 897

110.81 105.62 103.23 101.49 99.73 99.11 97.26 95.52 90.26 88.90 88.74 86.15 85.73 84.01 82.73

a

Average, annual, age-standardized rate per 100 000 person-years. Surveillance Epidemiology and End Results Program (National Cancer Institute).

b

Table 2.2 Lowest incidence rates of cancer of the trachea, bronchus and lung in men circa 1990 Registry

Cases

ASRa

India, Karunagappally (1991–1992) Thailand, Kohn Kaen (1990–1993) Peru, Lima (1990–1991) Costa Rica (1988–1992) India, Bombay (1988–1992) Singapore: Indian (1988–1992) India, Madras (1988–1992) Peru, Trujillo (1988–1990) India, Trivandrum (1991–1992) USA, New Mexico: American Indian (1988–1992) Ecuador, Quito (1988–1992) India, Bangalore (1988–1992) Mali, Bamako (1988–1992) Uganda, Kyadondo (1991–1993) India, Barshi, Paranda and Bhum (1988–1992)

58 355 635 686 1867 83 789 47 69 24 172 495 38 20 11

17.04 17.02 15.89 15.63 14.48 14.33 12.64 11.93 10.63 10.32 10.13 8.06 5.28 4.24 1.26

a

Average, annual, age-standardized rate per 100 000 person-years.

The finding of the incidence rate among women in Tianjin, China, among the 15 highest incidence rates recorded, is the first clear indication of the rising epidemic of lung cancer, and other cancers, resulting from the increasing prevalence of cigarette smoking during recent decades (Table 2.3). There are some regions of

the world where the incidence rate among women is still truly low (Table 2.4). In men in all European countries, except Portugal, lung cancer is now the leading cause of cancer death. In the USA (and in all European countries except a few Scandinavian countries), it is also the commonest tumor

Epidemiology of lung cancer: a century of great success and ignominious failure 15

Table 2.3 Highest incidence rates of cancer of the trachea, bronchus and lung in women circa 1990 Registry

Cases

ASRa

New Zealand: Maori (1988–1992) Canada, Northwest Territories (1983–1992) Canada, Yukon (1983–1992) USA, San Francisco: Black (1988–1992) USA, Detroit: Black (1988–1992) USA, New Orleans: White (1988–1992) USA, San Franciso: non-Hispanic White (1988–1992) USA, Detroit: White (1988–1992) USA, Central California: non-Hispanic White (1988–1992) USA, Los Angeles: non-Hispanic White (1988–1992) UK, Scotland, west (1988–1992) USA, SEER:b Black (1988–1992) USA, Hawaii: White (1988–1992) USA, Seattle (1988–1992) China, Tianjin (1988–1992)

326 80 39 562 1213 1115 3906 4772 2267 6674 5086 2558 340 4413 3870

72.93 65.56 47.62 44.33 42.02 41.19 40.42 40.17 39.48 38.58 38.47 38.46 37.94 37.62 37.00

a

Average, annual, age-standardized rate per 100 000 person-years. Surveillance Epidemiology and End Results Program (National Cancer Institute).

b

Table 2.4 Lowest incidence rates of cancer of the trachea, bronchus and lung in women circa 1990 Registry

Cases

Malta (1992–1993) France, La Réunion (1988–1992) France, Tarn (1988–1992) Spain, Albacete (1991–1992) Spain, Tarragona (1988–1992) Algeria, Setif (1990–1993) Spain, Granada (1988–1992) Spain, Zaragoza (1986–1990) India, Karunagappally (1991–1992) India, Madras (1988–1992) India, Trivandrum (1991–1992) India, Bangalore (1988–1992) Mali, Bamako (1988–1992) Uganda, Kyadondo (1991–1993) India, Barshi, Paranda and Bhum (1988–1992)

18 46 60 19 72 33 92 116 10 142 14 103 13 4 3

ASRa

3.35 3.34 3.19 3.14 3.09 2.88 2.71 2.66 2.59 2.37 1.89 1.67 1.53 0.41 0.33

a

Average, annual, age-standardized rate per 100 000 person-years.

in terms of incidence (although the recent inflation of prostate cancer incidence figures with very early detection of cases is taking prostate cancer above lung cancer in terms of the incidence of the disease). The range of geographic variation in lung cancer mortality in Europe is threefold in both sexes – the highest rates being observed in the UK, Belgium, the Netherlands, and the

former Czechoslovakia, and the lowest rates being reported in southern Europe and in Norway and Sweden.22 This overall pattern of age-standardized lung cancer mortality rates does not reveal the important and diverging cohort effects occurring in various countries: for instance, some of the countries in which there are now low rates, such as those in southern Europe

16 Textbook of Lung Cancer

and parts of eastern Europe, experienced a later uptake and spread of tobacco use, and now appear among the most elevated rates in the younger age groups. This suggests that these same countries, including Italy, Greece, France, Spain, and several countries in eastern Europe, will have the highest lung cancer rates in men at the beginning of the next century, in the absence of rapid intervention. The importance of adequate intervention is shown by the low lung cancer rates in Scandinavian countries, which have adopted, since the early 1970s, integrated central and local policies and programs against smoking.23,24 These policies may have been enabled by the limited influence of the tobacco lobby in these countries. The experience in Finland provides convincing evidence of the favorable impact, after a relatively short delay, of well-targeted large-scale interventions on the most common cause of cancer death and of premature mortality in general. With specific reference to women, current rates in most European countries (except the UK and Ireland) are still substantially lower than in the USA, where lung cancer is now the leading cause of cancer death in females. In several countries, including France, Switzerland, Germany, and Italy, where smoking is now becoming commoner in young and middle-aged women, overall national mortality rates are still relatively low, although appreciable upward trends have been registered over the last two decades. This is particularly worrisome in perspective, since smoking prevalence has continued to increase in subsequent generations of young women in these countries. Thus the observation that lung cancer is still relatively rare in women, with smoking at present accounting for only approximately 40–60% of all lung cancer deaths, cannot constitute a reason for delaying efficacious interventions against smoking by women. The currently more favorable situation in Europe compared with the USA, together with the observation that smoking cessation reduces lung cancer risk after a delay of several years, should, in the presence of adequate intervention, enable a major lung cancer epidemic in European women to be avoided. A proportion of lung cancers, varying in various countries and geographic areas, may be due to exposures at work, and a small proportion to atmospheric pollution.25 The effect of atmospheric pollution in increasing lung cancer risk appears to be chiefly confined to smokers. Lung cancer risk is elevated in atomic bomb survivors,26 in patients treated for ankylosing spondylitis,27 and in underground miners whose bron-

chial mucosa was exposed to radon gas and its decay products: this last exposure was reviewed and it was concluded that there was ‘sufficient evidence’ that this occupational exposure caused lung cancer.28 A greater risk of lung cancer is generally seen for individuals who are exposed at an older age. Investigation of the interaction with cigarette smoking among atomic bomb survivors suggests that it is additive,29 but the data from underground miners in Colorado are consistent with a multiplicative effect.30 In conclusion, the overwhelming role of tobacco smoking in the causation of lung cancer has been repeatedly demonstrated over the past 50 years. Current lung cancer rates reflect cigarette smoking habits of men and women over past decades,31–33 but not necessarily current smoking patterns, since there is an interval of several decades between the change in smoking habits in a population and its consequences on lung cancer rates. Over 90% of lung cancer may be avoidable simply through avoidance of cigarette smoking. Rates of lung cancer in central and eastern Europe at present are higher than those ever before recorded elsewhere; lung cancer has increased tenfold in men and eightfold in women in Japan since 1950; there is a worldwide epidemic of smoking among young women,34 which will be translated into increasing rates of tobacco-related disease, including cancer, in the coming decades; there is another epidemic of lung cancer and tobaccorelated deaths building up in China as the cohorts of men in whom tobacco smoking became popular reach ages at which cancer is an important hazard.35 Many solutions have been attempted to reduce cigarette smoking, and increasingly many countries are enacting legislation to curb this habit.36

PHASE IV: PUBLIC HEALTH FAILURE, 1960s ONWARDS Thus it has been clear for the entire second half of the 20th century that cigarette smoking causes lung cancer. Current low levels of smoking among physicians and research scientists in many countries have led many of them unconsciously to overlook tobacco smoking as an important cause of cancer.37 There is, however, a very substantial body of evidence from many sources that indicates the carcinogenicity of tobacco smoking. Not only does cigarette smoking greatly increase the risk of lung cancer in smokers, but the risk of oral cavity cancer, laryngeal cancer, esophageal cancer, bladder cancer, pancreatic cancer, and kidney cancer is also

Epidemiology of lung cancer: a century of great success and ignominious failure 17

increased. The risk of cancer of the cervix and stomach may also be increased, although the evidence for this is much less consistent.38 These forms of cancer can be expected to rise in women as a result of their increased levels of cigarette smoking. There is at present a worldwide epidemic of tobaccorelated disease: not only does smoking cause increased levels of many different common forms of cancer, it also increases the risk of cardiovascular disease. As mentioned in the previous section, deaths from lung cancer, the tumor most strongly linked to cigarette smoking, have increased in Japan by a factor of 10 in men and 8 in women since 1950. In central and eastern Europe, more than 400 000 premature deaths are currently caused each year by tobacco smoking. In young men in all countries of central and eastern Europe, there are current levels of lung cancer that are greater than anything seen before in the Western countries, and these rates are still rising. In Poland – a country severely hit by the tobacco epidemic – the life-expectancy of a 45-year-old man has been falling for over a decade now owing to the increasing premature death rates from tobacco-related cancers and cardiovascular disease.39 Tragically, cigarette smoking is still increasing in central and eastern Europe and also in China, where an epidemic of tobacco-related deaths is building up quickly. Tobacco smoking is also the most easily avoided risk factor for cancer. The most important determinant of risk of lung cancer is the duration of smoking: long-term cigarette smokers have a 100-fold increased risk compared with never-smokers. The content of cigarettes (low tar) produces only a threefold variation in risks between the extremes. (‘Low tar’ is frequently taken to include a number of features, including filter-tips as well as the active tar yield.) Lung cancer is the major tobacco-related tumor and the leading cause of cancer death in men in almost every developed country. Incidence rates are around 10–15 per 100 000 in non-smokers and between 80 and 100 per 100 000 in the highest-incidence population groups such as Afro-Americans, and rates exceeding 200 per 100 000 have been reported in cities of central and eastern Europe. Since lung cancer is frequently fatal, mortality rates are high, and consequently so are the social costs. Women around the world have taken up the cigarette smoking habit with gusto. For many years, it appeared that their lung cancer rates were low and that tobacco was not having the same effect as on men. This complacency, which crept in during the two decades from the mid-1960s especially, is now exposed as false:

nor is there evidence that the effect of cigarette smoking on lung cancer risk is greater in women than in men. The dominance of the effect of duration of smoking means that a long period of time will pass between the exposure (large numbers of women smoking) and the effect (high levels of lung cancer). Lung cancer now exceeds breast cancer as the leading cancer cause of death in women in the USA, Canada, Scotland, and several other countries. In Canada, breast cancer mortality has remained at least constant for nearly four decades, while lung cancer death rates have increased between three- and fourfold during the same period. While the higher case-fatality of lung cancer may be one factor in the mortality rates overtaking breast cancer, there is, increasingly, evidence that there are regions of the world where the gap in the incidence rate is now closing. For example, in Glasgow, an area where lung cancer has been historically high, by 1990 the incidence rate for lung cancer (115 per 100 000) exceeded that for breast cancer (105 per 100 000) in 1990.40 Among international cancer registries, there are some where the incidence of lung cancer now exceeds the incidence of breast cancer, and others where there is still a gap. In the SEER (Surveillance Epidemiology and End Results) Program of the US National Cancer Institute, the incidence of lung cancer in both Black and White women increased by over 90% between 1973–1977 and 1988– 1992: the increase in the incidence of breast cancer was around 25% in both racial groups (comparison made between incidence rates age-adjusted using the 1970 US population). It is a great worry that there does not appear to be any end in sight to this increase in lung cancer risk internationally: it is programmed to continue for several decades to come. Part of the complacency over the effect on women was also due to the strong tendency for women to smoke brands of cigarettes that were lower in tar and nicotine content than those smoked by men: it was assumed that these would have less of a risk for lung cancer than the higher-tar cigarettes that men generally smoked. Marked changes in the rates of the major histologic cell types of lung cancer can now be seen, with particular increases in the risk of adenocarcinoma.41,42 The changes seen are compatible with increased risk of adenocarcinoma due to increasing levels of smoking of ‘light’ cigarettes (low-tar, low-nicotine). It appears that abandoning high-tar cigarettes (15–45 mg tar) may have some impact on reducing squamous-cell carcinoma risk, but this is now being balanced by ‘light’ cigarettes increasing the risk of adenocarcinoma.

18 Textbook of Lung Cancer

Cigarette smoking kills half of all those who adopt the habit, with 50% of these deaths occurring in middle age and each losing an average of 20 years of non-smoker’s life expectancy.43 It kills in over 24 different ways, with the lung being the commonest cancer site.43 Lung cancer rates have been declining in men and increasing in women: cigarette smoking in men has been declining while it has been increasing in women. These two trends are closely related. The move to ‘light’ cigarettes, which is increasingly common, now appears to be linked to increases in adenocarcinoma of the lung, and shows no sign of being linked to a reduced risk overall. There is no such thing as a ‘safe cigarette’. Smokers should be urged and helped to stop smoking; children and young adults should be convinced not to smoke. Tobacco can become an addictive drug: it should be left alone.20

ACKNOWLEDGMENTS It is a pleasure to acknowledge that this work was conducted within the framework of support from the Associazione Intaliana per la Ricerca sul Cancro (Italian Association for Research on Cancer).

REFERENCES 1. Adler I. Primary Malignant Growths of the Lungs and Bronchi: A Pathological and Clinical Study. London: Longmans, Green and Co, 1912. 2. Tylecote FE. Cancer of the lung. Lancet 1927; ii: 256–7. 3. Fleckseder R. Ueber den Bronchialkrebs und einge seiner Entstehungsbedingungen. Munch Med Wochenschr Nr 1936; 36: 1585–93. 4. Ochsner A, Debakey M. Primary pulmonary malignancy. Treatment by total pneumonectomy. Analysis of 79 collected cases and presentation of 7 personal cases. Surg Gynecol Obstet 1939; 68: 435–51. 5. Muller FH. Tabaksmisbrauch und Lungenkarzinom. Z Krebsforsch 1940; 49: 57–85. 6. Schairer E, Schöniger E. Lungenkrebs und Tabaksverbrauch. Z Krebsforsch 1943; 54: 261–9. 7. Schrek R, Baker LA, Ballard GP, Dolgoff S. Tobacco smoking as an etiologic factor in disease. Cancer Res 1950; 10: 49–58. 8. Levin ML, Goldstein H, Gerhardt PR. Cancer and tobacco smoking. JAMA 1950; 143: 336–8. 9. Mills CA, Porter MM. Tobacco smoking habits and cancer of the mouth and respiratory system. Cancer Res 1950; 10: 539–42. 10. Wynder EL, Graham EA. Tobacco smoking as a possible etiologic factor in bronchiogenic carcinoma. JAMA 1950; 143: 329–36.

11. Doll R, Hill AB. Smoking and carcinoma of the lung. BMJ 1950; ii: 739–48. 12. Doll R, Hill AB. A study of the aetiology of carcinoma of the lung. BMJ 1952; ii: 1271–86. 13. US Public Health Services, Smoking and Health. Report of the Advisory Committee to the Surgeon General of the Public Health Service. US Department of Health, Education and Welfare, Public Health Service, Center for Disease Control, DHEW Publication 1103: Washington, DC, 1964. 14. United States Surgeon General, Smoking and Health. A Report of the Surgeon General. US Department of Health, Education and Welfare, Public Health Service, DHEW Publication (PHS) 79-50066: Washington, DC, 1979. 15. Hammond EC. Smoking in relation to death rates of one million men and women. Natl Cancer Inst Monogr 1966; 19: 127–204. 16. Cederlof R, Friberg L, Hrubec Z, Lorich U. The Relationship of Smoking and Some Social Covariates to Mortality and Cancer Morbidity. A Ten Year Follow-up in a Probability Sample of 55,000 Swedish Subjects Age 18–69, Parts 1 and 2. Stockholm: Karolinska Institute, 1975. 17. Bross IDJ, Gibson R. Risks of lung cancer in smokers who switch to filter cigarettes. Am J Publ Health 1968; 58: 1396–403. 18. Hammond EC, Garfinkel L, Seidman H, Lew EA. Some recent findings concerning cigarette smoking. In: Hiatt HH, Watson JD, Winsten JA, eds. Origins of Human Cancer. Book A: Incidence of Cancer in Humans. New York: Cold Spring Harbor Laboratory, 1977; 101–12. 19. Bouisson J. Du cancer buccal chez les fumeurs. Montpellier Med 1859; 2: 539–99. 20. Boyle P, Veronesi U, Tubiana M et al. School of Oncology Advisory Report to the European Commission for the ‘Europe Against Cancer Programme’ European Code Against Cancer. Eur J Cancer 1995; 9: 1395–405. 21. IARC (International Agency for Research on Cancer), Monographs on the Evaluation of Carcinogenic Risk to Humans. Vol 38. Tobacco Smoking. Lyon: IARC, 1986. 22. Levi F, Maisonneuve P, Filiberti R et al. Cancer incidence and mortality in Europe. Sozial-Präventivmedizin 1989; 34 (Suppl 2): 1–84. 23. Bjartveit K. Legislation and political activity. In: Zaridze DG, Peto R, eds. Tobacco: A Major International Health Hazard. Lyon: IARC, 1986; 285–98. 24. Della-Vorgia P, Sasco AJ, Skalkidis Y et al. An evaluation of the effectiveness of tobacco-control legislative policies in European Community countries. Scand J Soc Med 1990; 18: 81–9. 25. Tomatis L. Air Pollution and Human Cancer. European School of Oncology Monograph. Berlin: Springer-Verlag, 1990. 26. Shimizu Y, Kato H, Schull WJ et al. Life Span Study Report 11, Part 1: Comparison of Risk Coefficients for Site Specific Cancer Mortality Based on the DS86 and T65DR Shielded Kerma and Organ Doses. Radiation Effects Research Foundation Technical Report 12–87. Hiroshima: Radiation Effects Research Foundation, 1987. 27. Smith PG, Doll R. Mortality among patients with ankylosing spondylitis after a single treatment course with X-rays. BMJ 1982; 284: 449–54. 28. IARC (International Agency for Research on Cancer), Monographs on the Evaluation of Carcinogenic Risk to Humans. Vol 44. Alcohol Drinking. Lyon: IARC, 1988.

Epidemiology of lung cancer: a century of great success and ignominious failure 19 29. Kopecky KJ, Yamamoto T, Fujikura T et al. Lung Cancer, Radiation Exposure and Smoking Among A-Bomb Survivors, Hiroshima and Nagasaki, 1950–1980. Radiation Effects Research Foundation Technical Report 13–86. Hiroshima: Radiation Effects Research Foundation, 1987. 30. Whittemore AS, McMillan A. Lung cancer mortality among US uranium miners: a reappraisal. J Natl Cancer Inst 1983; 71: 489–99. 31. Boyle P, Robertson C. Statistical modelling of lung cancer and laryngeal cancer incidence data in Scotland, 1960–1979. Am J Epidemiol 1987; 125: 731–44. 32. Le Vecchia C, Franceschi S. Italian lung cancer death rates in young males. Lancet 1984; ii: 406. 33. La Vecchia C, Levi F, Decarli A et al. Trends in smoking and lung cancer mortality in Switzerland. Prev Med 1988; 17: 712–24. 34. Chollat-Traquet C. Women and Tobacco. Geneva: World Health Organization, 1992. 35. Boyle P. The hazards of passive and active smoking. N Engl J Med 1993; 328: 1708–9. 36. Roemer R. Legislative Action to Combat the World Tobacco Epidemic. Geneva: World Health Organization, 1993.

37. Boyle P. The hazards of passive and active smoking. N Engl J Med 1993; 329: 1581. 38. Boyle P. Cancer, cigarette smoking and premature death in Europe. A review including the recommendations of European Cancer Experts Consensus Meeting. Helsinki, October 1996. Lung Cancer 1997; 17: 1–60. 39. Zatonski WA, Boyle P. Health transformations in Poland after 1988. J Epidemiol Biol 1996; 1: 183–97. 40. Gillis CR, Hole DJ, Lamont DW et al. The incidences of lung cancer and breast cancer in women in Glasgow. BMJ 1994; 305: 1331. 41. Zheng T, Holford T, Boyle P et al. Time trend and age– period–cohort effect on the incidence of histologic types of lung cancer in Connecticut, 1960–1989. Cancer 1994; 74: 1556. 42. Levi F, Franceschi S, La Vecchia C et al. Lung carcinoma trends by histologic type in Vaud and Neuchatel, Switzerland, 197–1994. Cancer 1997; 79: 906–14. 43. Doll R, Peto R, Wheatley K et al. Mortality in relation to smoking: 40 years’ observations on male British doctors. BMJ 1994; 309: 901–11.

3

Molecular biology of lung cancer Thomas Tuxen Poulsen, Hans Skovgaard Poulsen, Helle Pappot Contents Introduction • Growth signals and lung cancer • Apoptosis in lung cancer • Aberrant anti-growth signaling • Replicative potential and telomerases • Angiogenesis • Tissue invasion and metastasis • Conclusion

INTRODUCTION It becomes more and more important to understand the biology of lung cancer as new therapeutic agents are emerging in the field of clinical oncology. These agents are often referred to as targeted therapy or biologic therapy. New advances in molecular technologies are providing insight into the pathobiology of lung cancer development. It is now known that clinical lung cancers have accumulated numerous clonal genetic and epigenetic alterations as a multistep process.1 In many research laboratories molecular studies are these days performed in an integrated approach with clinical investigators to find new ways for early diagnosis, risk assessment, prevention, and treatment for this frequent and deadly disease. In the following, the spectrum of molecular alterations in lung cancer are described as hallmarks of cancer, subdivided as suggested by Hanahan and Weinberg:2 • • • • • •

abnormalities in self-sufficiency signals; evading apoptosis; insensitivity to anti-growth signals; limitless replicative potential; sustained angiogenesis; tissue invasion and metastasis.

of

growth

GROWTH SIGNALS AND LUNG CANCER In tumor cells, activated (proto)oncogenes often encode molecules involved in aberrant growth factor signaling, either by directly promoting cell growth, by mimicking other growth factors, or by neutralizing growth inhibitory signals. Growth factors are proteins that bind to receptors (usually on the cell surface) and trigger activation of cellular proliferation and/or differentiation.

Normal cells depend on external growth stimulating signals to proceed from quiescence to proliferation and these growth stimuli are often provided by neighboring cells in the immediate microenvironment, for instance by release of diffusible growth factors or expression of cell adhesion molecules. These interrelations between the cell and its environment allow for establishment of normal tissue homeostasis with a tight regulation of tissue modeling, growth, and regeneration. Tumor cells have lost their dependency on growth stimulatory signals from the external environment and are fully capable of proliferating independently. This phenotype of growth autonomy is attained by a variety of molecular changes and gene mutations within the cell, typically characterized by a state of growth factor self-sufficiency, where the cell itself produces the required growth factors and receptors, resulting in a self-stimulatory autocrine signaling loop. Aberrant expression and signaling by a number of growth factors and cognate receptors have been identified, which increase the cellular proliferative potential in lung cancer. In non-small cell lung cancer (NSCLC) these include upregulation/mutation of certain receptor tyrosine kinases (RTKs), in particular the epidermal growth factor receptor (EGFR, ErbB1) and other members of the ErbB RTK family. In small cell lung cancer (SCLC) overexpression of insulin-like growth factor I (IGF-I) and its receptor as well as a number of neuronal growth stimulators is frequently observed. An overview of the changes in expression and signaling of central growth factors and receptors, signal transducers, and transcription factors in lung cancer is presented below and summarized in Table 3.1. The section will conclude with a presentation of related experimental therapeutic strategies developed to target these mediators for future treatment of lung cancer.

Molecular biology of lung cancer 21

Table 3.1 Growth signals and lung cancer Signaling mediators involved in activating growth signaling in lung cancer Aberrant activation/mutation frequency Oncogene

NSCLC (%)

SCLC (%)

References

EGFR HER2-Neu IGF-I C-Kit/C-Met K-ras Neuropeptides C-myc

50–90 ∼30 — — ∼20–30 16–47 up to 50

— — >95 Up to 70 — All 10–40

3, 4 33 9 12, 13 15 17 23, 24

Epidermal growth factor receptor overexpression and signaling in NSCLC Overexpression of EGFR occurs in 50–90% of all NSCLC and is particularly common in squamous cell carcinoma,3,4 whereas EGFR overexpression is rare in SCLC. The receptor is membrane associated and contains three main regions: an extracellular ligand binding domain, a hydrophobic membrane spanning region, and a cytoplasmic part holding the catalytic tyrosine kinase activity. Upon ligand binding, EGFR undergoes a conformational change, leading to dimerization of the receptor and activation of the intracellular catalytic domain by phosphorylation of tyrosine residues. The phosphorylated tyrosine residues serve as binding sites for a number of different downstream signaling molecules and adaptors within the cell. Three major signaling pathways downstream of EGFR are outlined in Figure 3.1. One of the most intensively studied cascades is the Ras/Raf/ERK pathway (the right-hand pathway in Figure 3.1). The effects of this pathway are diverse (for a review see reference 5), with a large number of Ras effectors, but in general Ras signaling upon EGF stimulation has been associated with increased cell growth and proliferation. One of the three ras genes, Kirsten-ras (K-ras, p21-ras), is mutated in ∼30% of NSCLC. The oncogenic impact of this mutation in lung cancer is discussed further below. Another central pathway in EGFR signaling involves activation of PI3-kinase and AKT (PKB). This pathway generally serves to promote cell survival, by inhibition of various cell cycle regulators such as glycogen synthase kinase 3 (GSK3) and the pro-apoptotic protein BAD (Figure 3.1, the middle pathway). A final key pathway activated by EGFR involves the activation of phospholipase C-γ (PLC-γ), resulting

in hydrolyzation of phosphoinositide 4,5-bisphosphate (PIP-2) to generate inositol-3-phosphate (IP3) and diacylglycerol (DAG) (Figure 3.1, the left-hand pathway). This results in the release of calcium ions from intracellular stores, which affects cell motility and migration by interfering with the activity of actin-modulatory proteins. The activation of PLC-γ also activates protein kinase C (PKC), which causes attenuation of EGFR signaling by a negative feedback mechanism. The different pathways by which activated EGFR exerts its proliferative, migratory, and anti-apoptotic effects, and the fact that many of the involved signaling modulators have been found to cross-react between pathways, provide a central, yet complex, role for EGFR in cell transformation. In NSCLC, increased EGFR signaling is obtained by an increased gene copy number and by activating mutations within the EGFR gene.6 One mutated EGFR variant termed EGFRvIII, commonly found in various malignancies including ∼16% of NSCLC, has gained increasing interest in recent years. EGFRvIII lacks the extracellular ligand-binding domain, rendering the receptor incapable of binding any ligands, yet the receptor is constitutively active and fully capable of activating downstream modulators.7 In recent years, novel activating mutations within the tyrosine kinase domain of EGFR have been identified in NSCLC. These mutations have gained massive interest, since they have been found to correlate with increased response to treatment with EGFR tyrosine kinase inhibitors.8 Another member of the ErbB family is HER2-Neu (ErbB2), which is overexpressed in ∼30% of NSCLC. No ligands for Her2-Neu have yet been identified but the receptor is a central dimerization partner for the other RTKs of the ErbB family. To date, results are

22 Textbook of Lung Cancer EGFR dimer

EGF

EGF

Membrane

DAG

PKC

PIP2 Raf

IP3

Ras

PLC-γ TK

TK

PI3K SOS SHC

Ca2+

MEK

GRB2 AKT Ca2+ Ca2+ Ca2+

Cytosol

GSK3

BAD

ERK

Nucleus Altered gene expression

- Increased cell growth and proliferation - Downregulation of apoptotic response - Increased cell motility/migration

Figure 3.1 EGFR signaling. Upon ligand binding EGFR dimerizes, resulting in a complex signaling response within the cell. Oncogenic EGFR signaling occurs through three major pathways: the Ras/ERK (right-hand), the PI3-kinase AKT (middle), and the phospholipase C-γ (left-hand) pathways, resulting in an increased malignant potential of the cells. For further explanation see text.

conflicting with regard to Her2-Neu overexpression and prognosis in NSCLC. Overexpression of other growth factor receptors and ligands The expression level of the mitogen IGF-I is elevated in the majority of SCLC, resulting in a self-stimulatory autocrine loop involving the IGF-I receptor which is commonly co-expressed in this malignancy.9 IGF signaling proceeds through binding of IGF ligands (IGF-I and II) to cell surface RTKs (IGF-IR and -IIR). The biologic activity of the signaling system is modulated by

binding of IGF binding proteins present in the extracellular fluids and serum to the IGF ligands. As for EGFR, activated IGF-IR signaling is complex but primarily occurs through the Ras/Raf/ERK and the PI3-kinase/ AKT pathways. A correlation between significantly elevated IGF-I serum levels and lung cancer risk has been reported, but results of other studies are conflicting.10,11 The RTK c-Kit and its ligand stem cell factor (SCF) is another receptor/ligand system, upregulated in more than 80% of SCLC tumors.12 A study of c-Kit expression in SCLC patients identified c-Kit as a marker for

Molecular biology of lung cancer 23

increased survival13 – an observation which appears contradictory to the oncogenic properties of c-Kit signaling. However, the patients enrolled in this study were receiving chemotherapy targeting actively dividing cells, and since activation of c-Kit induces cell proliferation, the active receptor may render the malignant cells more susceptible to cytotoxic treatment, thereby improving overall survival. c-Met is yet another RTK often overexpressed in SCLC. Signaling through this receptor system has been reported to be associated with tumor growth and metastasis. In contrast to the c-Kit/SCF system, the c-Met ligand hepatocyte growth factor (HGF) is rarely co-expressed with the receptor in SCLC,12 but is expressed and secreted from surrounding normal lung fibroblasts. This observation indicates a paracrine rather than autocrine activating loop of c-Met expression in lung cancer. The importance of paracrine c-Met signaling for lung cancer pathogenesis has been investigated further in a study where c-Met-expressing lung cancer cells were transplanted into HGF-overexpressing mice, resulting in increased metastatic potential of the transplanted cells.14 Activating Ras mutations As mentioned, mutations of the intracellular membraneassociated signaling mediator Ras (Figure 3.1, green pathway) with a high overrepresentation of mutations in the K-ras gene are detected in up to 30% of NSCLC,15 but rarely in SCLC patients. Ras protein becomes activated by the binding of guanine triphosphate (GTP), allowing for transmission of growth stimulatory signals to the cell nucleus. Downregulation of Ras signaling occurs by hydrolysis of GTP to GDP, mediated by the GTPase-activating protein (GAP). In NSCLC and other malignancies, activating point mutations in the K-ras gene result in resistance to GAP activity, thereby trapping the Ras protein in a constitutively active state, capable of continuous growth promoting signaling. Controversy exists as to whether K-Ras mutations serve as a marker for poor prognosis in lung cancer, but a global meta-analysis correlated the presence of pointmutated constitutively active Ras in NSCLC with a poor prognosis.16

G-protein-coupled receptors, resulting in activation of various downstream signaling pathways including PLC, PI3-kinase, and certain kinases, involved in cellular focal adhesion. Gastrin releasing peptide (GRP) signaling via the GRP receptor (GRP-R) has become one of the most intensively studied neuropeptide signaling pathways in SCLC, since different studies have shown that blocking GRP or GRPR activity inhibits SCLC cell growth in vitro and in vivo, whereas GRP addition to SCLC cells induces cell proliferation.18,19 The concentration of the GRP precursor pro-GRP is highly elevated in the majority of SCLC patients and levels decrease upon tumor resection, indicating that proGRP serum levels may serve as a detection and monitoring marker for patients with this disease. Other neuropeptides highly expressed in lung cancer include bradykinin, neuron specific enolase and L-Dopa decarboxylase. Whether these molecules play an oncogenic, growth-promoting role in lung cancer and/or whether they may potentially serve as clinical markers remains controversial. In recent years, the expression of the neuroendocrine transcription factor Achaete–Scute homolog 1 (ASH1) in SCLC has gained increased attention. ASH1 is normally expressed in neuronal progenitor cells during early fetal development of various tissues including the central nervous system and the lung. Expression is virtually absent in the normal adult organism, but ASH1 is reactivated and highly expressed in SCLC and in other lung tumors with a neuroendocrine phenotype, including a minority of large cell and adenocarcinomas. High expression of ASH1 seems to correlate with poor differentiation of these lung tumors, since expression is virtually absent in fully differentiated carcinoid tumors.20 Furthermore, ASH1 expression is tightly linked to classic neuroendocrine markers including L-Dopa decarboxylase. Although future research is clearly necessary to clarify the role of ASH1 in lung cancer pathogenesis, many studies suggest ASH1 expression as a critical pathogenic factor in neuroendocrine lung tumors. The overexpression of ASH1 induces lung tumors and cell hyperplasia in mouse models,21 and one study reported significant inhibition of SCLC cell growth after ASH1 knock out in vitro and in vivo.22

Overexpression of neuropeptides Highly elevated expression of different neuropeptides is a hallmark of SCLC and many of these markers have also been detected in some (mainly poorly differentiated) NSCLC tumors.17 Neuropeptides exert their effect via binding to seven transmembrane (7TM)

Amplification of myc Members of the c-myc, N-myc, and L-myc (proto)oncogene family are commonly amplified in SCLC and NSCLC, resulting in overexpression of Myc transcription factors.23,24 Myc protein competes with other transcription factors to bind Max, resulting in activation

24 Textbook of Lung Cancer

and repression of a number of genes. Although the contributions of myc amplification to lung cancer pathogenesis remain to be elucidated, recent studies point to a role for myc in promoting cell cycle progression by activation of key cell cycle molecules responsible for entry into the S-phase of the cell cycle (for a review of myc signaling in lung cancer see reference 25). In combination with loss of tumor suppressor genes such as Rb (the properties of which will be discussed in a later section), myc has been shown to significantly contribute to decreased cell cycle arrest and deregulated tumor growth.26 Experimental therapeutic targeting of growth factors and oncogenes in lung cancer In the previous sections, a number of different growth factors and oncogenes of importance for lung cancer biology have been presented. Knowledge gained about the properties of these molecules has allowed for the development of novel therapeutics targeting key activating, growth promoting, and tumorigenic pathways. A research area of major focus in recent years has been therapeutic targeting of EGFR in NSCLC. There are two general strategies for inhibiting signaling via EGFR. One is to prevent binding of ligand by blocking the ligand binding site (commonly with a monoclonal antibody) and the other is to directly inhibit receptor signaling by blocking activity of the cytoplasmic tyrosine kinase domain. Belonging to the first group, cetuximab is a humanized monoclonal EGFR antibody, which is presently under development and testing for treatment of NSCLC. The results of a recently published phase I/II clinical trial have shown an effect of cetuximab in combination with chemotherapy of NSCLC,27 and further clinical studies are ongoing at present. The two most clinically advanced RTK inhibitors are erlotinib and gefitinib, and erlotinib recently obtained FDA approval for second-line treatment of NSCLC. As previously mentioned, a number of mutations in the RTK domain of EGFR have been identified in NSCLC.8 Importantly, the presence of RTK mutations seems to correlate positively with the response to treatment with gefitinib, suggesting that these mutations may serve as classifiers for selecting the patients who will benefit from EGFR-RTK inhibiting treatments. As previously mentioned, the gene encoding the growth promoting Ras protein is mutated in up to 30% of NSCLC, making this protein a potential target for therapeutic intervention. Cytoplasmic Ras protein is

inactive and must be associated with the plasma membrane to contribute to cell signaling. For this association to occur, synthesized Ras protein is post-translationally modified by addition of a farnesyl group. Farnesylation is mediated by a specific enzyme – the farnesyl transferase – and targeting this reaction with farnesyl transferase inhibitors has been investigated clinically for treatment of lung cancer and other malignancies. Despite promising preclinical data and reported responses in patients with breast cancer and certain leukemias, the results of the use of farnesyl transferases for treating lung cancer have been disappointing, with lack of tumor regression in all of the clinical studies reported to date.28 The monoclonal antibody imatinib targets a number of RTKs including c-Kit and has been evaluated in two recent phase II studies for treatment of SCLC. Disappointingly, both studies report no inhibitory effect on tumor growth, even in patients with c-Kit-positive tumors.29,30 Apart from the clinical studies reported to date, a number of preclinical investigations have shown promise for anti-growth-signaling targeted therapy of lung cancer. Therapeutic blockade of IGF-I signaling by an IGF-IR-specific tyrosine kinase inhibitor has been reported to enhance the sensitivity of SCLC cells to chemotherapy in vitro, correlating with inhibition of the anti-apoptotic PKB signaling pathway.31 Finally, therapeutics have been developed which target neuronal markers overexpressed in lung cancer, primarily SCLC. However, a phase I clinical trial using an antibody targeting GRP in patients with SCLC reported no significant therapeutic response.32 In contrast, recent pre-clinical data showed growth suppression of SCLC cells after knockout of ASH1 in vitro and in vivo.22

APOPTOSIS IN LUNG CANCER Apoptosis is a morphologically and biochemically distinct form of cell death that occurs under various physiologic and pathologic conditions triggered by extrinsic and intrinsic cellular and molecular damage. It is characterized by the activation of a specific event of molecular processes followed by certain morphologic changes such as shrinkage of the cell, condensation of chromatin, and disintegration of the cell into small fragments. Today many of the key players in cellular apoptosis regulation have been identified and activators and inhibitors have been characterized and can therefore be targeted by therapeutic agents. Apoptosis is activated

Molecular biology of lung cancer 25

by a family of intracellular cysteine proteases called caspases. They are synthesized as zymogens and activated by proteolytic cleavage. They are divided into two distinct classes, initiator caspases, which include caspases P8, P9, and P10, and effector caspases, which include caspases P3, P6, and P7. Current knowledge suggests that there are two separate pathways of caspase activation. One starts with binding of an extracellular ligand to its cell surface receptor. The ligands are TNF, FasL, and Trail, and their respective receptors are TNFRI, FAS, and DR4 and DR5. The ligand binding triggers initiator caspase activation through a death inducing signaling complex (DISC), resulting in caspase-P8 activation of effector caspases, either directly or through BCL-2 interacting domain (BID)-mediated release of cytochrome c from mitochondria (Figure 3.2). The other caspase activation pathway starts with release of cytochrome c from the intermembrane space of mitochondria. Two proapoptotic family members, BAX and BAK, appear to facilitate cytochrome c release by participating in the

Death ligand

Death receptor pathway

Mitochondrial pathway

Membrane

Death receptor

PROCASP 8/10 FADD Mitochondria

BID BID DISC

Cytochrome c CASP 8 (CASP10) PROCASP 9 EXECUTIONER PATHWAY CASP3,6,7

APOPTOSIS

CASP 9

APAF1

Apoptosome

Figure 3.2 Apoptosis. Major pathways to apoptosis: two pathways lead to apoptosis, an extrinsic pathway through death receptors and an intrinsic pathway through the mitochondria. The two pathways overlap and interact.

formation of a pore that releases mitochondrial intermembrane space proteins. After its release, cytochrome c binds to apoptotic protease activating factor-1 (APAF-1). APAF-1 binds to procaspase-9 forming a multiprotein complex, called an apoptosome, which activates effector caspases through caspase-9 (Figure 3.2). Anti-apoptotic factors such as Bcl-2-related proteins antagonize BAX and BAK. In addition, IAP (inhibitor of apoptosis protein) binds and inhibits apoptosomerelated caspases. However, this inhibition can be relieved by the release of another mitochondrial protein, called Smac/Diablo, which binds to the IAP and releases active caspases. The most widely studied IAP is survivin. Activators and inhibitors are influenced by several other proteins including p53, RB, PTEN, Raf-ERK, PI3K-PKB, and Hsp70.33,34 The apoptotic pathways and possible defects have not been studied much in human lung cancer, and therefore only sporadic, non-conclusive data are available. However, recently it has been shown that DR4 and DR5 are upregulated in NSCLC, and overexpression of DR5 correlates with a poor prognosis in patients with NSCLC. Bcl-2 expression is higher in SCLC compared with NSCLC. Furthermore, data have indicated that the BAX:Bcl-2 ratio might be of importance for resistance to apoptosis. Caspase-8 and caspase-10 might be deregulated, and differences in deregulation in SCLC compared with NSCLC especially concerning caspase-8 have been observed, resulting in deregulation of DISC. Others have found that the apoptosome signaling might be blocked. In addition, it has been indicated that downregulation of caspase-3 is correlated with a poor prognosis in patients with NSCLC.33,35 Survivin is increased in most NSCLC and it has been shown that absence of its expression might be associated with improved prognosis. In addition, previously unpublished microarray data show that survivin is upregulated in SCLC in human cell lines, xenografts, and resected tumors from patients (Figure 3.3)36 (Poulsen HS, unpublished data). Targeting apoptotic pathways Treatment with TNF has been undertaken. However, due to pronounced general toxicity, its potential as a therapeutic drug is limited. Recently TRAIL agonists have been approved for clinical trials but no data are presently available. Small molecule inhibitors of Bcl-2 have been developed and are at the moment being tested in preclinical trials. In addition, antisense constructs against survivin have been produced and tested in phase I clinical trials.

26 Textbook of Lung Cancer 250

Microarray signal

200

150

100

50

Normal tissues

SCLC cell lines and xenografts

SCLC tumor 1 SCLC tumor 2 SCLC tumor 3 SCLC tumor 4 SCLC tumor 5 SCLC tumor 6

CPH 54A CPH 54A Xeno CPH 54B CPH 136A Xeno GLC 2 GLC 3 GLC 3 Xeno GLC 14 GLC 14 Xeno GLC 16 GLC 19 GLC 26 GLC 28 DMS 53 DMS 79 DMS 92 DMS 114 DMS 153 DMS 273 DMS 273 Xeno DMS 406 DMS 456 H69 H69 Xeno NCI 417 NCI 417 Xeno MAR H24 MAR H24 Xeno MAR 86H

Fetal brain Brain Adrenal gland Colon Heart Kidney Liver Lung Pancreas Prostate Salivary gland Skeletal muscle Small intestine Spleen Stomach Testes Thyroid Trachea

0

Tumors

Figure 3.3 Survivin in SCLC. Survivin mRNA expression in SCLC cell lines, xenografts, and resected patient tumors compared with normal tissue.

In addition, an adenovirus-based gene therapy approach targeting survivin is under development.37

ABERRANT ANTI-GROWTH SIGNALING

A review of key tumor suppressors, frequently mutated in lung cancer is presented below and summarized in Table 3.2, followed by an update within the field of tumor suppressor reactivation in experimental lung cancer therapy.

Apart from upregulation of growth stimulatory signaling, cancer cells often lack expression of a number of tumor suppressors. In contrast to oncogenes, tumor suppressor genes act to prevent and control cell growth, often via tight control of cell cycle progression. Full inhibition of tumor suppressor activity often requires inactivation of both alleles of a tumor suppressor gene in the cancer cell. This dual inactivation is frequently accomplished by a two-step process, involving a chromosomal translocation or deletion resulting in loss of heterozygosity (LOH), followed by an inactivating point mutation of the remaining allele. In lung cancer cells, LOH of distinct chromosomal regions is frequently detected and many of these regions harbor genes encoding central tumor suppressors, known or speculated to be involved in cancer pathogenesis. Tumor suppressor activity may also be inhibited by dominant negative mutations, which actively inhibit the activity of wildtype protein binding partners within the cell. Finally, epigenetic alterations (i.e. mutation-independent mechanisms) have in recent years gained increased attention in the regulation of tumor suppressor knock-down.

Tp53 mutations The transcription factor p53 is one of the most intensely studied tumor suppressors. The Tp53 gene is located within a region of chromosome 17 (17p13), which is mutated or altered in the majority of lung cancers with a specifically high prevalence in SCLC and squamous cell carcinoma.38,39 The types of Tp53 alterations observed in lung cancer range from gross chromosomal changes such as LOH, homozygous deletions, and DNA rearrangements, to local point mutations,40 all of which contribute to Tp53 malfunction or inactivation. The p53 protein is a key player in the cellular response to stress, acting as a gatekeeper of the cell cycle. Activation of p53 signaling in normal cells generally occurs in response to different types of cellular stress including DNA damage, aberrant oncogenic growth factor signaling, and exposure to extracellular factors such as chemotherapeutics and UV light. The level of p53 protein and activity within the cell is regulated at the level of degradation rather than the level of synthesis and, under normal conditions, the protein is rapidly degraded within the cell. The cellular enzyme

Molecular biology of lung cancer 27

Table 3.2 Aberrant anti-growth signaling Tumor suppressor gene mutations/inactivations and LOH in lung cancer Mutation/inactivation frequency Tumor suppressor gene

Chromosome location

NSCLC (%)

SCLC (%)

References

Tp53 RB p16INK4a TGFbRII LOH 3p

17p13 13q14 9p21 3p22 3p regions

∼50 ∼30 ∼70 ∼44 70–100

∼80 ∼90 ∼10 <75 >90

43 44, 61 45, 61 48, 62 51, 52

MDM2 plays an important role in the downregulation of p53. MDM2 serves as a p53 binding partner, which facilitates the attachment of ubiquitin tags to p53, thereby targeting it for degradation. Furthermore, MDM2-bound p53 activates transcription of the MDM2 gene, resulting in increased MDM2 levels, p53 ubiquitinylation, and degradation. Upon lowering of the p53 concentration, fewer MDM2–p53 complexes are formed, resulting in reduced MDM2 transcription and decreased p53 degradation. As such, the MDM2–p53 interaction generates an oscillating feedback loop of p53 and MDM2 degradation and synthesis within the cell (Figure 3.4). Activation of p53 requires post-translational modifications (such as acetylation, glycosylation, and addition of phosphate groups), some of which may inhibit p53 degradation by inhibiting its binding to MDM2. This is the case upon DNA damage, where activation of different proteins such as ATM-kinase and DNA-dependent kinase facilitates the phosphorylation of p53 at sites involved in the interaction with MDM2, resulting in p53 activation (Figure 3.4). Active p53 regulates transcription of a number of genes involved in cell cycle control (such as cyclindependent kinase inhibitors), resulting in cell cycle arrest, thus allowing for repair of damaged DNA by the cellular repair machinery. Activation of p53 also induces apoptosis via activation of a number of apoptotic mediators (including Bax) and inhibits blood vessel formation by activation of genes encoding anti-angiogenic factors. A frequent observation in lung cancer cells with mutated p53 is accumulation of p53 within the cell, due to increased stability of the mutated protein.41 A number of studies have investigated the prognostic role of p53 mutations in lung cancer patients, and although the results are somewhat conflicting, accumulating evidence suggests that p53 mutations result in a

poorer prognosis in NSCLC. Given the high abundance of p53 mutations in SCLC patients, the limited number of patients with intact p53 signaling limits prognostic studies in this malignancy. For a detailed review of p53 mutations in lung cancer, and the clinical impact of these aberrations, see reference 42. Mutated RB and p16INK4a A central tumor-suppressing signaling cascade, frequently altered in human lung cancer, is the p16INK4a/ CDK-cyclin-D/Rb pathway. The retinoblastoma (RB) tumor suppressor gene located at 13q14 encodes a transcription factor involved in the regulation of G1 to S-phase transition in the cell cycle. The tumorsuppressing activity of Rb depends on its level of phosphorylation. In its hypophosphorylated state, Rb binds to and inhibits the activity of different binding partners, including members of the E2F family of transcription factors. Upon phosphorylation of Rb, E2F is released and activated, resulting in transcription of genes responsible for G1 to S-phase cell cycle progression (Figure 3.5). Consequently, Rb in its hypophosphorylated state serves as a tumor suppressor. Phosphorylation of Rb is mediated by different complexes of cell cycle proteins such as cyclin D and CDK4 and 6. The formation of these complexes is inhibited by p16INK4a, which thereby serves as a tumor suppressor upstream of Rb by indirectly inhibiting its phosphorylation and thereby promoting Rb association with its binding partners (Figure 3.5). Inactivation of the RB gene by LOH and/or mutation is observed in 90% of SCLC tumors,43 whereas the p16INK4a gene is frequently inactivated in NSCLC,44 resulting in lack of activity of the Rb tumor suppressor pathway in virtually all lung cancers. These findings indicate that inactivation of this pathway is a mandatory step in the pathogenesis of pleural malignancies. The p16INK4a gene locus is located at chromosome 9p21,

28 Textbook of Lung Cancer DNA damage p14ARF Decreased p53 activity

MDM2 p53

ATM-kinase/DNA dependent kinase

INCREASED MDM2-SYNTHESIS

MDM2

p14ARF MDM2 ACTIVE p53

Altered gene expression

- Cell cycle arrest - Apoptosis - Anti-angiogenesis`

Figure 3.4 p53 signaling. In normal cells p53 plays a key role in regulation of the cellular response to a number of stress factors, but the p53 protein is frequently mutated in lung cancer and other malignancies. Under normal conditions p53 activity is inhibited by the binding of MDM2 to the protein. Upon cellular exposure to stress, cellular proteins such as p14ARF and specific kinases (i.e. ATM-kinase and DNA-dependent kinase) release p53 from MDM2 inhibition, resulting in activation of p53. This again may result in cell cycle arrest, apoptosis, and anti-angiogenic signaling.

which is a region frequently subjected to LOH in NSCLC.45 Apart from p16INK4a, the same locus also encodes the tumor suppressor p14ARF through an alternative reading frame. The p14ARF protein is known to bind to MDM2, thereby inhibiting ubiquitinylation and degradation of p53 (Figure 3.4). Furthermore, E2Fs are known to activate p14ARF transcription, providing a functional link between the Rb and p53 tumor suppressor pathways. Aberrant TGFβ signaling The transforming growth factor β (TGFβ) receptor system is also commonly altered in lung cancer. In contrast to the growth factor receptor systems described in previous sections, the effects of signaling by TGFβ are mostly associated with inhibited cellular proliferation in many cell types. TGFβ signaling is mediated via serine-threonine-kinase receptors that can be divided into two subgroups termed TGFβRI and II. Lack of response to TGFβ (termed TGFβ resistance) in SCLC has been correlated with lack of TGFβRII,46,47 and this

association was recently confirmed by the introduction of functional TGFβRII into receptor-negative lung cancer cells, resulting in restored sensitivity to TGFβ.48 TGFβ signaling is associated with a number of cellular functions, the best described of which relate to inhibition of the cell cycle. Growth inhibitory effects of TGFβ signaling have been associated with inhibition of expression and assembly of some of the cyclin/CDK components responsible for Rb activation.49 Loss of chromosome 3p and related genes Probably the most frequent chromosomal abnormality in lung cancer is loss of regions within chromosome 3p. LOH at chromosome 3p has been reported in 70–100% of all NSCLC and more than 90% of SCLC.50,51 A number of genes within this region have been suggested as putative tumor suppressors. The loss of the fragile histidine triad (FHIT) gene located at position 3p14.2 is frequent in lung cancer, with more extensive genetic lesions occurring in highergrade tumors compared with low-grade and premalignant lesions.52 Accumulating evidence points to a role of FHIT as a tumor suppressor. Expression of FHIT protein in NSCLC cell lines and mouse xenograft models has been shown to suppress tumor growth and induce apoptosis,53 and recently FHIT has been found to stabilize p53 presumably by interaction with MDM2, which thereby becomes incapable of binding and ubiquitinylating p53.54 This points to a functional role of FHIT in apoptotic signaling, although the exact function of FHIT remains to be fully elucidated. RASSF1A is a different candidate tumor suppressor gene residing at chromosome 3p (position 3p21). This gene is inactivated in virtually all SCLC and more than 60% of NSCLC.55,56 Apart from allelic loss, the RASSF1A gene has been found to be inactivated by epigenetic mechanisms and hypermethylation of distinct regions (so called CpG islands) within the promoter of the RASSF1A gene, which inhibits gene transcription. Reintroduction of RASSF1A has been found to reduce colony formation, suppress anchorage-independent growth, and inhibit tumorigenicity of NSCLC cells in vitro and in nude mice.55 Furthermore, RASSF1A has been shown to associate with microtubules, and recently overexpression of RASSF1A has been reported to inhibit motility of NSCLC cells and increase cell adhesion, suggesting a role for RASSF1A in cell migration and metastasis.57 Several other genes reside at the frequently deleted regions of chromosome 3p but much remains to be learned about the role of these genes in tumor suppression. For a review of candidate tumor suppressor

Molecular biology of lung cancer 29

CDK4/6

CYCLIN D

p16INK4a Rb

E2F

Rb

CDK4/6 CYCLIN D

P

ACTIVE E2F

Altered gene expression

- Cell cycle progression - Cell proliferation - Anti-apoptosis

Figure 3.5 Rb signaling. The Rb–p16INK4a–tumor suppressor pathway, which is frequently mutated in lung cancer, acts by inhibiting the activation of the E2F family of transcription factors responsible for growth promoting and anti-apoptotic signaling within the cell. p16INK4a, which is frequently mutated in NSCLC, acts by inhibition of the cyclin-CDK4/6 complex responsible for release of E2F from Rb inhibition. In SCLC, Rb itself is frequently mutated, rendering the protein incapable of inhibiting E2F signaling. The high frequency of Rb and p16INK4a mutations in SCLC and NSCLC, respectively, suggests that inhibition of this pathway is 0mandatory in the development of pleural malignancies.

genes residing at chromosome 3p which may play a role in lung cancer pathogenesis see reference 58. Experimental treatments: reintroduction of tumor suppressors Since the loss of activity of certain tumor suppressor pathways is a distinctive characteristic of human lung cancer, reintroduction of tumor suppressor activity is an attractive strategy for therapeutic intervention. For this purpose, replacement gene therapy by delivery of lost tumor suppressor genes to cancer cells has become increasingly attractive. Most reports of tumor suppressor replacement gene therapy of lung cancer involve reintroduction of TP53 in NSCLC, where a number of clinical trials have been published. In general, the treatment has been found to be well tolerated and responses have been observed in terms of tumor regression and disease stabilization in some of the enrolled patients. However, the limiting factor of gene therapy today remains poor delivery of the therapeutic gene to the cancer cells. The clinical studies performed

to date have all used modified viruses for gene delivery. Although the delivery rates using viral systems have been improved, a major drawback of using viruses for gene delivery is the induction of immune responses against the virus in the patients. This results in the production of antibodies which target the virus for degradation and limit the efficiency of repeated treatments. Novel non-viral delivery vehicles are being developed, which may in the future provide a potent alternative to viral gene therapy. The status within the field of replacement gene therapy for lung cancer and delivery vector development has recently been reviewed.59 Reintroduction of other tumor suppressor genes in lung cancer has been evaluated in preclinical studies. Co-delivery and expression of FHIT and TP53 have been reported to provide a synergistic tumor-suppressing effect in NSCLC in vitro and in vivo.54 Future studies will be necessary to assess the potential of these strategies for treatment of lung cancer patients.

REPLICATIVE POTENTIAL AND TELOMERASES When cultures of differentiated somatic cells are established in vitro they have a well-defined potential for cell division. After a number of divisions, the cells are predetermined to enter crisis, a state characterized by extensive cell death and chromosomal aberrations. This phenomenon has been termed the mitotic clock and is part of the tight regulation of normal cell growth. In contrast, cancer cells propagated in culture have an unlimited potential for continuous cell division and are said to be immortalized. The molecular explanation for the mitotic clock resides in the chromosomal structure and mechanism of DNA replication. Upon cell division, the cell initiates DNA replication which proceeds to produce new leading and lagging strands from the DNA double helix. Since DNA replication can only proceed in one direction (3′–5′), only the leading strand of the double helix is continuously synthesized, whereas the new lagging strand is assembled by ligation of smaller DNA fragments. The discontinuous replication of the lagging strand results in a gap at the 5′ end of the newly synthesized DNA strand, resulting in loss of chromosomal material during each mitotic cycle. The chromosomal ends are termed telomeres and are composed of six nucleotide repeats. The telomeres are involved in the correct orientation of the chromosomes during cell division. Due to the continuous shortening of telomeric DNA following cell division,

30 Textbook of Lung Cancer

lack of telomere maintenance ultimately results in chromosomal degradation and end-to-end chromosome fusion, exemplified by the massive cell death observed during the crisis state of untransformed cells cultured in vitro. In order to overcome the limitation of telomere shortening, cancer cells activate a program for telomere maintenance, which is normally shut down in fully differentiated normal cells. Most frequently, this is accomplished by activation of an enzyme complex known as telomerase, but a subset of cancer cells lacks telomerase activity and are immortalized by a process known as alternative lengthening of telomeres (ALT). The implications of the telomere-activating machinery in lung cancer and the development of therapeutic strategies targeting telomere maintenance are discussed below. Telomere maintenance in lung cancer The core telomerase enzyme comprises an RNA subunit (hTERC) which provides the template for synthesis of new telomeric DNA facilitated by the catalytic subunit human telomerase reverse transcriptase (hTERT). The RNA component hTERC is ubiquitously expressed in many cells, whereas hTERT expression is normally confined to undifferentiated cells such as germ line cells and bone marrow stem cells, identifying the enzyme moiety as the limiting factor for telomere maintenance. Indeed, the great majority of SCLC and NSCLC expresses the enzyme hTERT,60 whereas hTERT expression and telomerase activity has been found to be repressed in the majority of lung carcinoids, a malignancy which is also associated with a longer-term survival.61 A number of studies have shown that increased telomerase activity and increased levels of hTERT mRNA are mainly found in patients with poorly differentiated tumors (such as SCLC) and advanced disease and correlate with poor survival, suggesting telomerase activity as an important prognostic marker for patients with lung cancer.62,63 A number of alternative splice variants of hTERT mRNA, many of which lack enzymatic activity, have been identified, but the prognostic value and molecular role of these mutations in lung malignancies remain to be clarified. As previously mentioned, a small subset of cancer cells acquires telomere maintenance without activation of telomerase by a process termed ALT. Although this phenomenon remains to be fully elucidated, ALT appears to involve recombination of chromosome ends in a mechanism associated with DNA replication.64 No studies reporting ALT in lung cancer have been published to date, and whether ALT plays a role in lung cancer cell immortalization therefore remains to be elucidated.

Experimental therapeutic targeting of telomerase in lung cancer Due to the central role of telomerase in the transformation of lung cancer cells, and the lack of telomere maintenance in normal tissues, blocking the activity of this enzyme appears an intriguing target for therapeutic intervention. A number of small molecular inhibitors of telomerase activity have been developed and some of these agents have been reported to inhibit the growth of NSCLC cells in vitro, albeit with a delay in growth inhibition of several months after the initiation of treatment.65 The compound GRN136L is a lipid-modified oligonucleotide, which binds to the hTERC subunit of telomerase with high affinity, thereby inhibiting reverse transcription by blocking access of hTERT to its RNA template. GRN136L has recently been reported to successfully inhibit telomerase activity, leading to telomere shortening and resulting in decreased growth of adenocarcinoma cells in vitro and effective prevention of tumor metastasis in a xenograft mouse model.66 Another strategy involves activation of an immune response towards telomerase by administration of a vaccine composed of hTERT-derived peptides. Recently a clinical phase I/II study investigating the effect of treatment with two hTERT peptides in patients with advanced NSCLC was published,67 reporting the treatment to be well tolerated and detecting immune responses towards telomerase in 11 and tumor response to treatment in 2 of 24 patients. A new clinical trial is being planned, aiming to investigate the effect of telomerase immunogenic peptides in combination with chemo- and radiotherapy.

ANGIOGENESIS The vasculature is crucial for cell function and survival in all tissues, since oxygen and nutrients are supplied by the vessels. The growth of new blood vessels, called the process of angiogenesis, is a normal physiologic process taking place under organogenesis, which under these conditions is transitory and carefully regulated.2 In a similar way tumors must develop angiogenic ability to progress. This ability appears by activating the angiogenic switch. The activation is probably a result of the change in the balance of angiogenesis inducers and countervailing inhibitors, e.g. by altered gene transcription. Angiogenesis can be described as a result of a dynamic balance between pro-angiogenic factors and anti-angiogenic factors.68 Once a tumor has activated its

Molecular biology of lung cancer 31

angiogenic switch it becomes able to grow; in the absence of this activation the tumor remains in a dormant state and is unable to grow in size beyond a few millimeters. Angiogenesis, however, involves more components than pro- and anti-angiogenic factors only. For succesfull angiogenesis, interactions between tumor cells, activation of the endothelial cells and mature vessels, degradation of the surrounding basement membrane, and invasion and migration of endothelial cells into the surrounding connective tissue are needed. Hereby tumor-associated neovascularization can take place by establishing continuity with the systemic circulation, allowing tumor survival and growth and, more seriously, facilitating further metastatic spreading. Many different pro- and anti-angiogenic factors have been identified. The angiogenesis-initiating signals are exemplified by vascular endothelial growth factor/ vascular permeability factor (VEGF/VPF) and acidic and basic fibroblast growth factors (FGF1/FGF2), which all bind to transmembrane tyrosine kinase receptors displayed by endothelial cells.69 The typical angiogenesis inhibitor is thrombospondin-1, which binds to CD36, a transmembrane receptor on endothelial cells coupled to intracellular Src-like tyrosine kinases.70 In total there are up to nearly one hundred different proand anti-angiogenic factors. These include platelet-derived endothelial cell growth factor (PE-ECGF), platelet-derived growth factor (PDGF), EGF, angiogenin, angiotensin II, platelet-activating factor (PAF), and the inhibitor angiostatin. Most of the molecules involved in angiogenesis are not specific to vascular endothelial cells, but have a broad spectrum of target cells, except from VEGF, which activates only endothelial cells. VEGF is a heparin-binding glycoprotein, which binds selectively to two high-affinity tyrosine kinase cell surface receptors: VEGFR1 and VEGFR2. These receptors are found in blood vessels within or near tumors, and the expression is found to be upregulated in most cancers including lung cancer. VEGF has been demonstrated to be an important predictor of poorprognosis in NSCLC.71 Targeting angiogenic factors Inhibiting angiogenesis through anti-angiogenic and/or vascular targeting agents seems logical, as new anti-cancer treatment strategies. In particular, much attention has focused on targeting VEGF and VEGFR. Compounds currently under investigation in cancer therapy include anti-VEGF/VEGFR antibodies, small molecule VEGFR tyrosine kinase inhibitors, antisense suppression of VEGF, immunotherapy, viral-directed targeting of

VEGFR signaling, ribozymes, and various toxin conjugates.72 Furthermore, blocking angiogenesis may enhance conventional anti-cancer treatments such as radiation therapy in situations where tumors are unresponsive to current anti-growth factor efforts, and the benefits of combining angiogenic inhibitors with radiation are being explored. Recent clinical trials have shown that the anti-VEGF antibody bevacizumab, combined with standard first-line chemotherapy in NSCLC, provided a statistically and clinically significant survival advantage with tolerable toxicity.73 In addition, more recently tested compounds characterized as antivasculature agents have been shown to be effective against mutiple targets; the efficiency of such compounds is currently being investigated in clinical trials for NSCLC.

TISSUE INVASION AND METASTASIS As mentioned above, cancer cells and tissues often have dysregulation of crucial processes and factors, such as apoptosis, growth factors, angiogenesis, replication potential, sensitivity to anti-growth signaling, and invasion and metastasis. Many of these processes are dependent on proteases, making proteases an interesting target for new anti-cancer treatments. Proteases (proteolytic enzymes) are highly involved in invasion and metastasis by degradation of the extracellular matrix, e.g. basement membranes. Proteases are involved in both extra- and intracellular protein degradation. Under normal conditions proteolysis is a physiologic process leading to, for example, wound healing, but in the malignant tumor proteolysis becomes a harmfull factor enabling tumor cells to move out, invade adjacent tissues, and thence travel to distant sites where they may succeed in founding new colonies, metastases (Figure 3.6), which are the cause of 90% of human cancer deaths.74 Thus, based on the degradation of extracellular proteins and basement membranes by proteolytic enzymes, increased invasion and metastasis can take place in malignant diseases. The major components of the basement membrane and the extracellular matrix are type IV collagen, laminin, fibronectin, vitronectin, and proteoglycans. Tumor cells can produce a number of proteolytic enzymes which can degrade these protein structures, including matrix metalloproteinases (MMPs), collagenases, urokinase plasminogen activator (uPA), plasmin, cathepsins, and others. MMPs are known to play a functional role in the metastatic spread of lung cancer.75 Different MMPs are active in

32 Textbook of Lung Cancer

Extravasation Intravasation

Regional lymph node metastasis

Survival in circulation

Growth in new environment

Figure 3.6 Metastasis. This diagram illustrates the importance of proteolysis in cancer, leading to tissue degradation, invasion, and metastasis.

different steps of the invasive and metastatic process, and a better understanding of the involvement of MMPs in the invasion and regulation of growth of both primary and metastatic tumors may help to implement these as anti-cancer therapy targets. Cathepsins have been demonstrated to have a prognostic value in NSCLC and levels of the receptors for uPA (uPAR) and other components of the plasminogen activation system are associated with survival in NSCLC.76 Targeting proteases and the metastatic process It is expected that inhibition of the metastatic potential of a tumor by interaction with extracellular protein degradation could be an important target, especially during early tumor development. Drugs targeting MMPs have been in clinical trials, but have shown little or no activity in lung cancer. Inhibition of MMPs has especially been focused on targeting MMP-2 and -9. In studies on cell lines and xenografts, the MMP inhibitor batimastat has shown an ability to decrease the invasion of cancer cells and to prolong survival in the treated animals. However, these finding have been most consistent in pancreatic cancer. The efficacies of batimastat and another MMP inhibitor marimastat have been tested in different solid tumor types, but the studies have been limited by toxicity. In the clinical phase I and II studies performed to date, little or no activity has been reported in lung cancer. At the moment new MMP inhibitors such as CP-471,358 are being evaluated in phase I and II studies in a number of malignancies including lung cancer.77 CONCLUSION As is evident from the preceding sections, major advances in molecular biologic research during recent decades

have resulted in a substantial insight into important signaling pathways and mediators contributing to lung cancer pathology. Recently, the first novel therapeutic, which directly targets growth-promoting pathways, was approved for treatment of lung cancer and many other drugs are presently under clinical investigation. However, although some patients respond well to the new treatments, it has become evident that further insight into the mechanism of action of many of these novel agents must be gained, in order to better individualize the targeted treatments to the patients who will benefit. Gaining further knowledge into the complexity of molecular lung cancer biology, correctly applying this knowledge in the development of novel therapeutics, and optimization of presently available agents therefore represent important challenges in lung cancer research and clinics for the years to come. REFERENCES 1. Fong KM, Sekido Y, Gazdar AF et al. Lung cancer. 9: Molecular biology of lung cancer: clinical implications. Thorax 2003; 58: 892–900. 2. Hanahan D, Weinberg RA. The hallmarks of cancer. Cell 2000; 100: 57–70. 3. Rusch V, Baselga J, Cordon-Cardo C et al. Differential expression of the epidermal growth factor receptor and its ligands in primary non-small cell lung cancers and adjacent benign lung. Cancer Res 1993; 53 (10 Suppl): 2379–85. 4. Selvaggi G, Novello S, Torri V et al. Epidermal growth factor receptor overexpression correlates with a poor prognosis in completely resected non-small-cell lung cancer. Ann Oncol 2004; 15: 28–32. 5. Shields JM, Pruitt K, McFall A et al. Understanding Ras: ‘it ain’t over ‘til it’s over’. Trends Cell Biol 2000; 10: 147–54. 6. Hirsch FR, Witta S. Biomarkers for prediction of sensitivity to EGFR inhibitors in non-small cell lung cancer. Curr Opin Oncol 2005; 17: 118–22.

Molecular biology of lung cancer 33 7. Pedersen MW, Meltorn M, Damstrup L, Poulsen HS. The type III epidermal growth factor receptor mutation. Biological significance and potential target for anti-cancer therapy. Ann Oncol 2001; 12: 745–60. 8. Paez JG, Janne PA, Lee JC et al. EGFR mutations in lung cancer: correlation with clinical response to gefitinib therapy. Science 2004; 304: 1497–500. 9. Reeve JG, Payne JA, Bleehen NM. Production of immunoreactive insulin-like growth factor-I (IGF-I) and IGF-I binding proteins by human lung tumours. Br J Cancer 1990; 61: 727–31. 10. Yu H, Spitz MR, Mistry J et al. Plasma levels of insulin-like growth factor-I and lung cancer risk: a case-control analysis. J Natl Cancer Inst 1999; 91: 151–6. 11. Lukanova A, Toniolo P, Akhmedkhanov A et al. A crosssectional study of IGF-I determinants in women. Eur J Cancer Prev 2001; 10: 443–52. 12. Rygaard K, Nakamura T, Spang-Thomsen M. Expression of the proto-oncogenes c-met and c-kit and their ligands, hepatocyte growth factor/scatter factor and stem cell factor, in SCLC cell lines and xenografts. Br J Cancer 1993; 67: 37–46. 13. Rohr UP, Rehfeld N, Pflugfelder L et al. Expression of the tyrosine kinase c-kit is an independent prognostic factor in patients with small cell lung cancer. Int J Cancer 2004; 111: 259–63. 14. Yu Y, Merlino G. Constitutive c-Met signaling through a nonautocrine mechanism promotes metastasis in a transgenic transplantation model. Cancer Res 2002; 62: 2951–6. 15. Gao HG, Chen JK, Stewart J et al. Distribution of p53 and K-ras mutations in human lung cancer tissues. Carcinogenesis 1997; 18: 473–8. 16. Mascaux C, Iannino N, Martin B et al. The role of RAS oncogene in survival of patients with lung cancer: a systematic review of the literature with meta-analysis. Br J Cancer 2005; 92: 131–9. 17. Kiriakogiani-Psaropoulou P, Malamou-Mitsi V, Martinopoulou U et al. The value of neuroendocrine markers in non-small cell lung cancer: a comparative immunohistopathologic study. Lung Cancer 1994; 11: 353–64. 18. Thomas F, Arvelo F, Antoine E et al. Antitumoral activity of bombesin analogues on small cell lung cancer xenografts: relationship with bombesin receptor expression. Cancer Res 1992; 52: 4872–7. 19. Weber S, Zuckerman JE, Bostwick DG et al. Gastrin releasing peptide is a selective mitogen for small cell lung carcinoma in vitro. J Clin Invest 1985; 75: 306–9. 20. Jiang SX, Kameya T, Asamura H et al. hASH1 expression is closely correlated with endocrine phenotype and differentiation extent in pulmonary neuroendocrine tumors. Mod Pathol 2004; 17: 222–9. 21. Linnoila RI, Zhao B, DeMayo JL et al. Constitutive Achaete–Scute homologue-1 promotes airway dysplasia and lung neuroendocrine tumors in transgenic mice. Cancer Res 2000; 60: 4005–9. 22. Osada H, Tatematsu Y, Yatabe Y et al. ASH1 gene is a specific therapeutic target for lung cancers with neuroendocrine features. Cancer Res 2005; 65: 10680–5. 23. Brennan J, O’Connor T, Makuch RW et al. Myc family DNA amplification in 107 tumors and tumor cell lines from patients with small cell lung cancer treated with different combination chemotherapy regimens. Cancer Res 1991; 51: 1708–12.

24. Broers JL, Viallet J, Jensen SM et al. Expression of c-myc in progenitor cells of the bronchopulmonary epithelium and in a large number of non-small cell lung cancers. Am J Respir Cell Mol Biol 1993; 9: 33–43. 25. Zajac-Kaye M. Myc oncogene: a key component in cell cycle regulation and its implication for lung cancer. Lung Cancer 2001; 34 (Suppl 2): S43–6. 26. Santoni-Rugiu E, Falck J, Mailand N et al. Involvement of Myc activity in a G(1)/S-promoting mechanism parallel to the pRb/ E2F pathway. Mol Cell Biol 2000; 20: 3497–509. 27. Thienelt CD, Bunn PA Jr, Hanna N et al. Multicenter phase I/II study of cetuximab with paclitaxel and carboplatin in untreated patients with stage IV non-small-cell lung cancer. J Clin Oncol 2005; 23: 8786–93. 28. Johnson BE, Heymach JV. Farnesyl transferase inhibitors for patients with lung cancer. Clin Cancer Res 2004; 10(12 Pt 2): 4254–7s. 29. Dy GK, Miller AA, Mandrekar SJ et al. A phase II trial of imatinib (ST1571) in patients with c-kit expressing relapsed small-cell lung cancer: a CALGB and NCCTG study. Ann Oncol 2005; 16: 1811–16. 30. Krug LM, Crapanzano JP, Azzoli CG et al. Imatinib mesylate lacks activity in small cell lung carcinoma expressing c-kit protein: a phase II clinical trial. Cancer 2005; 103: 2128–31. 31. Warshamana-Greene GS, Litz J, Buchdunger E et al. The insulin-like growth factor-I receptor kinase inhibitor, NVPADW742, sensitizes small cell lung cancer cell lines to the effects of chemotherapy. Clin Cancer Res 2005; 11: 1563–71. 32. Chaudhry A, Carrasquillo JA, Avis IL et al. Phase I and imaging trial of a monoclonal antibody directed against gastrin-releasing peptide in patients with lung cancer. Clin Cancer Res 1999; 5: 3385–93. 33. Shivapurkar N, Reddy J, Chaudhary PM, Gazdar AF. Apoptosis and lung cancer: a review. J Cell Biochem 2003; 88: 885–98. 34. Jäättelä M. Multiple cell death pathways as regulators of tumour initiation and progression. Oncogene 2004; 23: 2746–56. 35. Fennell DA. Caspase regulation in non-small cell lung cancer and its potential for therapeutic exploitation. Clin Cancer Res 2005; 11: 2097–105. 36. Pedersen N, Mortensen S, Sorensen SB et al. Transcriptional gene expression profiling of small cell lung cancer cells. Cancer Res 2003; 63: 1943–53. 37. Fischer U, Schulze-Osthoff K. Apoptosis-based therapies and drug targets. Cell Death Differ 2005; 12 (Suppl 1): 942–61. 38. Chmara M, Wozniak A, Ochman K et al. Loss of heterozygosity at chromosomes 3p and 17p in primary non-small cell lung cancer. Anticancer Res 2004; 24: 4259–63. 39. Petersen I, Langreck H, Wolf G et al. Small-cell lung cancer is characterized by a high incidence of deletions on chromosomes 3p, 4q, 5q, 10q, 13q and 17p. Br J Cancer 1997; 75: 79–86. 40. Takahashi T, Nau MM, Chiba I et al. p53: a frequent target for genetic abnormalities in lung cancer. Science 1989; 246: 491–4. 41. Iggo R, Gatter K, Bartek J et al. Increased expression of mutant forms of p53 oncogene in primary lung cancer. Lancet 1990; 335: 675–9. 42. Campling BG, el Deiry WS. Clinical implication of p53 mutation in lung cancer. Mol Biotechnol 2003; 24: 141–56. 43. Hensel CH, Hsieh CL, Gazdar AF et al. Altered structure and expression of the human retinoblastoma susceptibility gene in small cell lung cancer. Cancer Res 1990; 50: 3067–72.

34 Textbook of Lung Cancer 44. Otterson GA, Kratzke RA, Coxon A et al. Absence of p16INK4 protein is restricted to the subset of lung cancer lines that retains wildtype RB. Oncogene 1994; 9: 3375–8. 45. Merlo A, Gabrielson E, Askin F, Sidransky D. Frequent loss of chromosome 9 in human primary non-small cell lung cancer. Cancer Res 1994; 54: 640–2. 46. Norgaard P, Damstrup L, Rygaard K et al. Growth suppression by transforming growth factor beta 1 of human small-cell lung cancer cell lines is associated with expression of the type II receptor. Br J Cancer 1994; 69: 802–8. 47. Hougaard S, Norgaard P, Abrahamsen N et al. Inactivation of the transforming growth factor beta type II receptor in human small cell lung cancer cell lines. Br J Cancer 1999; 79: 1005–11. 48. Anumanthan G, Halder SK, Osada H et al. Restoration of TGFbeta signalling reduces tumorigenicity in human lung cancer cells. Br J Cancer 2005; 93: 1157–67. 49. Laiho M, DeCaprio JA, Ludlow JW et al. Growth inhibition by TGF-beta linked to suppression of retinoblastoma protein phosphorylation. Cell 1990; 62: 175–85. 50. Kok K, Osinga J, Carritt B et al. Deletion of a DNA sequence at the chromosomal region 3p21 in all major types of lung cancer. Nature 1987; 330: 578–81. 51. Naylor SL, Johnson BE, Minna JD, Sakaguchi AY. Loss of heterozygosity of chromosome 3p markers in small-cell lung cancer. Nature 1987; 329: 451–4. 52. Wistuba II, Behrens C, Virmani AK et al. High resolution chromosome 3p allelotyping of human lung cancer and preneoplastic/preinvasive bronchial epithelium reveals multiple, discontinuous sites of 3p allele loss and three regions of frequent breakpoints. Cancer Res 2000; 60: 1949–60. 53. Ji L, Fang B, Yen N et al. Induction of apoptosis and inhibition of tumorigenicity and tumor growth by adenovirus vector-mediated fragile histidine triad (FHIT) gene overexpression. Cancer Res 1999; 59: 3333–9. 54. Nishizaki M, Sasaki J, Fang B et al. Synergistic tumor suppression by coexpression of FHIT and p53 coincides with FHIT-mediated MDM2 inactivation and p53 stabilization in human non-small cell lung cancer cells. Cancer Res 2004; 64: 5745–52. 55. Dammann R, Li C, Yoon JH et al. Epigenetic inactivation of a RAS association domain family protein from the lung tumour suppressor locus 3p21.3. Nat Genet 2000; 25: 315–19. 56. Burbee DG, Forgacs E, Zochbauer-Muller S et al. Epigenetic inactivation of RASSF1A in lung and breast cancers and malignant phenotype suppression. J Natl Cancer Inst 2001; 93: 691–9. 57. Dallol A, Agathanggelou A, Tommasi S et al. Involvement of the RASSF1A tumor suppressor gene in controlling cell migration. Cancer Res 2005; 65: 7653–9. 58. Zabarovsky ER, Lerman MI, Minna JD. Tumor suppressor genes on chromosome 3p involved in the pathogenesis of lung and other cancers. Oncogene 2002; 21: 6915–35. 59. Poulsen TT, Pedersen N, Poulsen HS. Replacement and suicide gene therapy for targeted treatment of lung cancer. Clin Lung Cancer 2005; 6: 227–36. 60. Hiyama K, Hiyama E, Ishioka S et al. Telomerase activity in small-cell and non-small-cell lung cancers. J Natl Cancer Inst 1995; 87: 895–902.

61. Gomez-Roman JJ, Romero AF, Castro LS et al. Telomerase activity in pulmonary neuroendocrine tumors: correlation with histologic subtype (MS-0060). Am J Surg Pathol 2000; 24: 417–21. 62. Marchetti A, Bertacca G, Buttitta F et al. Telomerase activity as a prognostic indicator in stage I non-small cell lung cancer. Clin Cancer Res 1999; 5: 2077–81. 63. Lantuejoul S, Soria JC, Moro-Sibilot D et al. Differential expression of telomerase reverse transcriptase (hTERT) in lung tumours. Br J Cancer 2004; 90: 1222–9. 64. Muntoni A, Reddel RR. The first molecular details of ALT in human tumor cells. Hum Mol Genet 2005; 14 (Spec No 2): R191–6. 65. Damm K, Hemmann U, Garin-Chesa P et al. A highly selective telomerase inhibitor limiting human cancer cell proliferation. EMBO J 2001; 20: 6958–68. 66. Dikmen ZG, Gellert GC, Jackson S et al. In vivo inhibition of lung cancer by GRN163L: a novel human telomerase inhibitor. Cancer Res 2005; 65: 7866–73. 67. Brunsvig PF, Aamdal S, Gjertsen MK et al. Telomerase peptide vaccination: a phase I/II study in patients with nonsmall cell lung cancer. Cancer Immunol Immunother 2006; 55: 1553–64. 68. de Castro JG, Puglisi F, de Azambuja E et al. Angiogenesis and cancer: a cross-talk between basic science and clinical trials (the ‘do ut des’ paradigm). Crit Rev Oncol Hematol 2006; 59: 40–50. 69. Veikkola T, Karkkainen M, Claesson-Welsh L, Alitalo K. Regulation of angiogenesis via vascular endothelial growth factor receptors. Cancer Res 2000; 60: 203–12. 70. Bull HA, Brickell PM, Dowd PM. Src-related protein tyrosine kinases are physically associated with the surface antigen CD36 in human dermal microvascular endothelial cells. FEBS Lett 1994; 351: 41–4. 71. Imoto H, Osaki T, Taga S et al. Vascular endothelial growth factor expression in non-small-cell lung cancer: prognostic significance in squamous cell carcinoma. J Thorac Cardiovasc Surg 1998; 115: 1007–14. 72. Raben D, Helfrich B. Angiogenesis inhibitors: a rational strategy for radiosensitization in the treatment of non-small-cell lung cancer? Clin Lung Cancer 2004; 6: 48–57. 73. Yano S, Matsumori Y, Ikuta K et al. Current status and perspective of angiogenesis and antivascular therapeutic strategy: non-small cell lung cancer. Int J Clin Oncol 2006; 11: 73–81. 74. Sporn MB. The war on cancer. Lancet 1996; 347: 1377–81. 75. Brown PD, Bloxidge RE, Stuart NS et al. Association between expression of activated 72-kilodalton gelatinase and tumor spread in non-small-cell lung carcinoma. J Natl Cancer Inst 1993; 85: 574–8. 76. Pedersen H, Brunner N, Francis D et al. Prognostic impact of urokinase, urokinase receptor, and type 1 plasminogen activator inhibitor in squamous and large cell lung cancer tissue. Cancer Res 1994; 54: 4671–5. 77. Planting A, van der GA, Schoffski P et al. A phase I and pharmacologic study of the matrix metalloproteinase inhibitor CP-471,358 in patients with advanced solid tumors. Cancer Chemother Pharmacol 2005; 55:136–42.

4

Tobacco policy Nigel Gray Contents Introduction • Basic policy • Developing countries • The future

INTRODUCTION The single global public health objective in this field is to reduce consumption of tobacco by all possible means as quickly as possible. Major successes such as the decline in British consumption and mortality are currently matched by the steep ascent of these two indices in developing countries, particularly China,1 which illustrates the urgency of policy action. It is reasonable to assert that implementation of policy lags, sometimes decades, behind policy development, which lags similarly behind the development of knowledge. In a number of sophisticated countries, among which are the UK, Norway, Sweden, Australia, Canada, and the USA, the proportion of the population which continues to smoke has fallen from over a half to about a quarter. Mortality declines have usually followed, but at very different rates. So it is wrong to be pessimistic but important to be impatient. Pressing for activist policies, on the grounds that outcomes take a long time, seems to be an integral part of the duty of the health professions. Comprehensive tobacco policy has been well established and understood since the mid-1970s.2 The recommendations in this chapter are informed by long experience of successful and unsuccessful policies in many diverse countries. Many of the important policy issues and outcomes have never been the subject of refereed articles in the technical press, so the reader must be satisfied with basic references and must be willing to search newspaper archives for historic detail. Tobacco use has been, and is, perhaps the most difficult issue faced by public health workers in the 20th century. Historic diseases such as smallpox, polio, measles, diphtheria, tetanus, whooping cough, rubella, and scarlet fever were conquered in developed countries within a decade or so of the arrival of effective control systems. When vaccines and antibiotics worked, they were used. Failures in developing countries relate to the failure of national and international social organization and rarely to organized opposition. The reappearance

of malaria and tuberculosis, depressing though it is, is partly due to these factors and partly due to the lack of really effective means of control. The singular feature of the tobacco problem is that someone is selling it. No one is selling tuberculosis. To this can be attributed the fact that, five decades after discovering its carcinogenicity, tobacco consumption worldwide is falling very slowly. Comparisons with the other industries selling toxic products are unsatisfactory. There is no pretence that asbestos does not cause asbestosis, nor that drunken driving is merely a pleasurable habit. The international tobacco industry is unique in its stubborn refusal to concede the sideeffects of its product, despite revelations3 which make it clear that the industry knew of the carcinogenic and addictive properties of tobacco some decades ago. Once having retreated into its legal bunker it is now in the difficult position of facing enormous legal and financial consequences if it makes concessions or tells the truth. Thus the forces of public health and the global tobacco industry are locked in continuous warfare and prospects for peace are slight. While no form of tobacco use has been discovered to be safe, the cigarette is the most ubiquitous, widely used, and best-studied product. The myriad forms of tobacco use seen in India and other parts of Asia are carcinogenic in many different ways and, being personally grown or based on cottage industry production, each poses specific individual problems. Certainly it is easier to develop policies to control cigarette smoking than tobacco/betel chewing as the product is factory made, taxed, exported and imported, and often the subject of retail licensing. The unrepentant nature of the global tobacco industry, which is controlled by relatively few major manufacturers, is reflected in the sales statistics. Sales are in decline in the most developed countries and the expected indices follow. Lung cancer in males, especially younger ones, is declining, as is heart disease.1 By contrast, tobacco exports from the USA are climbing and the antique tobacco monopolies of the previously

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communist world are being replaced by modern mass production systems owned by the same people. Marketing measures forbidden in the USA, UK, and Europe are rampant in many developing countries. Consideration of tobacco policy may conveniently focus first on the cigarette. Such consideration should take note that smoking is a learned habit which is initiated by social forces but sustained by the development of addiction in persistent users.

•

BASIC POLICY This is theoretically simple: • • • •

change the cultural background; change the smoker; change the cigarette; protect the children.

Changing the cultural background The cultural background against which tobacco smoking must be considered is a mixture of community law and community norms. Laws usually arise as a result of public opinion at a point in time and are an important reflection of community norms, although they do not always mirror public opinion in those countries where the tobacco industry is strongest. The failed battle to introduce strong tobacco legislation in the USA in 1998 shows the difficulties in the path of lawmakers that are posed by the organized and well-funded opposition of tobacco manufacturers. This situation, while obvious in the USA, arises in most countries when tobacco policy requires lawmaking, although the opposition may be less obvious and behind the scenes. An important element in the interaction between government, parliaments, and popular opinion may be non-government organizations. Policy frequently arises in the non-government sector, as may the drive for legislation. Thus the interactive process of introducing legislation may be an important part of providing a driving force for implementation. Popular laws are more likely to be implemented. Opposition to standard comprehensive laws is to be expected and is routinely led by those with vested interests, supported by the industry, using arguments now outdated and often ugly when exposed to public gaze.

•

•

•

Model legislation • •

Health warnings These should state government policy and the facts. Rotating, explanatory warnings

are the first step. Warnings researched for understandability and offering a telephone number to an information service are better. Warnings with graphic pictures are even better. Packet labeling There is a powerful case for generic packaging as a way of interfering with global brand advertising. Packaging should declare yields of known major carcinogens and other substances, which may be specified as knowledge develops. Packet inserts are a way of providing the sort of comprehensive information that is given with such substances as aspirin. Tobacco industry claims for the right to compete for adult markets are specious as adults and children co-exist in society and measures to protect or attract children often impinge on adults and vice versa. Abolition of promotion – in every form Tobacco brand names need to be forbidden in advertisements for any other product. Direct and indirect advertising needs to be specifically addressed. This issue remains difficult because of the cross-border abilities of satellite media. It should be understood that there is no case which can be made in favor of tobacco promotion as the product is seriously and chronically toxic when used as the manufacturers intend. Evasion of promotional restrictions is the profession of a large number of people, all of whose arguments should be ignored. Even at point of sale, advertisement should be forbidden. Availability Sales to children, defined as 16–18 in most countries, need to be prohibited and the prohibition policed. Such legislation is widespread, but policing is not. Vending machine sales need to be supervised in places inaccessible to children, or forbidden. This policy measure is widely adopted but almost nowhere has policing been tried. Until that experiment is done and shown to fail this issue remains high on the agenda for developing countries. Smoke-free environments These need encouragement for exemplary as well as risk-avoidance reasons. Schools, hospitals, workplaces, and public transport should be smoke-free, as a minimum. Smokers in many countries have been remarkably accepting of this policy. It is an important downward pressure on smoking rates in all age groups, and probably reduces daily dose as well as encouraging quitting. Tax This should be high in the context of individual income and should be regularly increased; a set proportion should be allocated to health purposes

Tobacco policy 37

•

including tobacco education.4 Tobacco tax is among the only taxes demonstrated to be popular. There is good reason why the price of a packet of cigarettes should be several times that of a hamburger. Regulation of the product It is unacceptable that a product as dangerous as tobacco should be unregulated. Additives need to be demonstrated to be non-toxic in both burnt and unburnt form; and upper limits should be set, and continuously reviewed, for major carcinogens and toxins. Public health advisors and departments have been slow to act in this field, possibly because of perceived complexities. However, the establishment of upper limits for cigarette emissions is relatively straightforward and is in need of urgent implementation.

The importance of legislation is underlined by the experience of Norway, the pioneer, in 1975, of comprehensive tobacco legislation. Tobacco consumption peaked in the mid-1970s, having risen by about 25% between the mid-1950s and mid-1970s. Since then it has declined by approximately the same amount. The original legislation in Norway was from a unanimous parliament, but was surrounded by much discussion and public interaction. This early legislation did not include severe workplace and public place restrictions, and Norwegian prices have risen only slightly, in real terms, since the 1980s.5 While it is possible to argue over the potential benefits of more aggressive pricing, public education, and smoking opportunity restrictions, the Norwegian experience is a testimony to the efficacy of good legislation as the basis for a comprehensive anti-tobacco program. Community norms are usually well reflected in public opinion. A comprehensive tobacco policy would include regular surveys of tobacco consumption, public opinion, relevant attitudes among smokers and nonsmokers, and evaluation of education programs. Opinion may move slowly, but it does move with time and in the presence of well-directed education programs. It is both logical and true that parental attitudes and example flow through to youth behavior, so changing the cultural background implies measuring beliefs and recruiting all the potential role models of society as well as removing the tobacco industry’s ability to promote its product. It is also logical to believe that education programs work better without opposition, further underlining the importance of complete eradication of promotion. In summary, changing the cultural background requires an activist and persistent approach to legislation

and community involvement. This means that a wellorganized and co-ordinated anti-smoking movement is a necessary basis. Such movements are not always large; efficiency and co-ordination are the keys. Changing the smoker Changing the smoker to become a non-smoker is a complex multifaceted process requiring analysis of individual society’s smoking patterns. It is accepted that addiction to tobacco is the major force in maintaining smoking status. Progress towards becoming a nonsmoker may be generally and simply summarized: Rational information → dissonance → attempts to quit → success → maintenance Dissonance may be defined as dissatisfaction with one’s own smoking behavior, and affects a majority of smokers in the USA, for example, but probably a minority in less well-informed societies. Clearly dissonance is more likely to occur if the victim/person is well informed, so the place of varied education programs, targeted to the subgroups as well as the totality of smokers, cannot be doubted, but is country-specific, at least to a degree. Other factors can be expected to stimulate dissonance: the smoke-free workplace and public places; peer group and family pressure; negative peer group experiences such as deaths or disease; societal attitudes and levels of information. Such factors reflect the cultural background and vary from country to country. Attempts to quit occur frequently in sophisticated countries and policy should encourage and provide support for smokers who make them. The role of nicotine replacement therapy (NRT) is crucial and in need of considerable development. Its value is well established although results are generally disappointing by comparison to expectations. Better products are needed as is greater availability and more support services. It is bizarre that cigarette content is virtually unregulated while bureaucratic restrictions on alternative sources of clean nicotine are widespread. The general global failure of health professionals, especially physicians, in support of patients and provision of therapy is a disturbing reflection of health priorities, which at least means there is hope for potential improvement. The debate over nicotine addiction6 per se ought not to hold back development of better products and services. Tobacco is a uniquely toxic way of delivering the desired dose of nicotine while NRT appears to be safe or relatively so. Up to this time there is no evidence of

38 Textbook of Lung Cancer

mass addiction to nicotine chewing gum, although the lack of competitive products which will deliver the quick, efficient, ‘fix’ of the cigarette might well explain this. Nevertheless, policy should be aimed at providing support, NRT, and whatever other pharmaceutical aids may be developed, since the status quo is an ongoing disaster which justifies greater effort than it receives. Continuing use of NRT in smokers who cut down but do not abstain is a sensible form of harm reduction, although the obvious goal is abstinence. Policy makers should note that the costs of helping smokers are infinitely less than those of treating them and that, while the most immediate mortality, morbidity, and cost benefits are achieved by attention to longduration heavy smokers, every smoker is at risk sooner or later, and early intervention is always best.

learned in reducing vehicle emissions to the cigarette, and to base regulations upon it. It is known8,9 there is great diversity in the levels of major carcinogens in mainstream smoke yields on the world market, so the evidence that cigarettes with lower carcinogen levels can be made and sold is indisputable – cigarettes low in nitrates and nitrosamines are made and sold. The policy issues then become the following: •

•

• Changing the cigarette The cigarette is a uniquely efficient nicotine delivery device which has so far escaped significant production controls worldwide. This is in contrast to motor vehicles, pharmaceuticals, food, houses, and even sewage systems. While the reasons for this disparity are interesting, as they include corruption on a global scale, there can be no excuse for continuing to allow the tobacco industry alone to decide what will go into the product, and therefore what is present in mainstream smoke. First it is necessary to state that the policy of the 1960s, which favored reduction of tar and nicotine levels over time, has not produced the benefits anticipated. Changes in cigarette design7 have brought about reductions in some carcinogens and increases in others. Mortality benefit, if present, is small, and adenocarcinoma has increased in the USA and elsewhere. Since tar measurement takes no account of the qualitative changes which have occurred in smoke it is misleading. Over the same time, bioavailability of nicotine has been increased and, together with compensatory smoking, means the machine-measured levels of nicotine are also misleading. It can therefore be unequivocally stated that tar and nicotine measures as currently used should be abolished – the policy question is what they should be replaced with? It must be recognized that cigarette design is best understood by the tobacco industry and is clouded by commercial secrecy, and that no governments have applied the necessary research resources to know enough to tell manufacturers how to make their product. However, it is certainly possible to apply the principles

•

•

•

•

Governments must claim power to regulate the content of cigarette smoke – this power exists in some countries. Health authorities require suitable advisory systems involving independent scientists and with mandatory access to industry information. Initially, major carcinogens such as benzo(a)pyrene, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and N-nitrosonornicotine (NNN) should be targeted. Market analysis would show the range of yields. Those cigarettes yielding above the median should be removed from the market, or modified, within a standard period such as 12 months. Over time this process would allow progressive reduction in carcinogens and other toxins, since the starting point is a level found to exist on the market and already achieved by at least some manufacturers. Nicotine needs special treatment. The first essential is a new measurement system. However, a measure which measures smoke content will not accurately reflect what gets into the smoker’s bloodstream, as it cannot control for compensatory smoking practices. Therefore, while control of smoke yield can be exerted by a measure such as nicotine content per liter of smoke, the decision-making process which sets the yield levels needs to be informed by behavioral experiment and analysis. The ultimate policy decision – whether mass weaning of nicotine-dependent populations should be attempted by regulatory reduction of dose per cigarette – cannot be made in the light of knowledge in 2007. However the goal of reduction in the addictiveness of the cigarette is a proper one and should be pursued as a matter of policy. In facing the decision to control nicotine yields, policy makers must understand that the rise of cigarette smoking was a vast unplanned experiment performed by the tobacco industry, initially ignorant of its product’s toxicity. Long-term decisions on nicotine policy will require similarly large

Tobacco policy 39

•

experiments based on sensibly considered probabilities. The decision to reduce tar and nicotine was sensible when conceived but subverted by industry manipulation. This mistake should not be made again but should not prevent innovative regulatory policies. New products containing tobacco ought also to be regulated and only tested in situations similar to those which are used for the testing of new pharmaceuticals. So far the tobacco industry has not produced a successful alternative to the standard cigarette. They should not be discouraged from doing so but should not receive marketing advantages over NRT and other nicotine alternatives.

ongoing smokers need to be related to those of children to a smoke-free and promotion-free environment. Policy is not only about prohibitions and restraints. There is a clear need for experimentally based, expensive, education programs aimed at children. The fact that few of these have been developed outside a few richer countries, and even fewer adequately funded, is not an excuse for failure to change. Every society which spends money on treating sick smokers would be well advised to spend funds of the sort spent on promotion of cola drinks on campaigns aimed at discouraging smoking.

DEVELOPING COUNTRIES Protecting the children As social norms and fashions have changed over time, so have the specific stimuli which trigger or contribute to initiation of the smoking habit. Age of onset of initiation varies around the world, beginning earlier in developed countries. Cultural differences play an important role, as exemplified by the great diversity in smoking rates between men and women in countries such as China. Whereas the factors which contribute to initiation in particular societies differ, the policy question is what can be done to interfere with the pressures toward initiation – or in simple terms, what can be done to protect the children? The first policy approach is to remove or reduce all the pro-smoking pressures which can be controlled. Formal and informal promotion of tobacco has been dealt with above. Nevertheless, it must be re-emphasized that children are extremely sensitive to promotional pressures and that any presentation of a tobacco brand name needs to disappear from the social environment. This has been substantially achieved in a number of countries, but has been subverted to a variable degree by cross-border advertising of events such as motor races and cricket matches sponsored by tobacco interests. Global control of this phenomenon will not be achieved easily, but the battle, slowly being won in developed countries, needs to be fought in developing countries as the industry seeks to source such events from them. Local social pressures need policy attention. The role of parents, siblings, peer groups, and local and international role models should be the subject of education programs and local campaigns, with the specific objective of reducing initiating pressures wherever they exist. What happens in schools, homes, workplaces, and public places needs detailed consideration. The rights of

Tobacco use is already built in to many developing countries and takes many forms. No form of tobacco use has been shown to be free of risk and the fact that snuff use in Sweden is less hazardous than tobacco/ betel chewing in India is not sufficient to allow fantasies of safe tobacco products to intrude on public policy. The principles set out above are applicable to some degree with most forms of tobacco use. However, local cultures in which the many and strange variants of tobacco smoking and chewing persist need to be considered individually. The broad-brush weapons of education, warning labels, taxation, and restriction where relevant can be considered by policy makers, and locally suitable policies developed and tried. The after-effects of tobacco use as known are such that no variant of use can be neglected. The reappearance of the cigar as a social status symbol in the USA should warn against complacency.

THE FUTURE The basic principles of tobacco policy discussed here have been tested and appraised in real societies and shown to work to a greater or lesser degree. The degree usually depends on the enthusiasm with which policies are implemented. The force of the vested interests of the tobacco industry has been able to slow policy implementation, but the fact remains that tobacco use in developed countries had declined substantially and the tobacco industry is now seeking to replace its lost, dying, and dead smokers in developed countries with new users in the poor and developing world. The political battle over the proposed tobacco settlement in the USA in 1998, although seemingly lost at

40 Textbook of Lung Cancer

that time, is a serious and important indication of the degree to which the international tobacco industry has declined in power and influence. It is to be expected that the public health principles espoused here will be applied progressively and more rapidly over the next decade. The result can only minimize the tobacco mortality epidemic already set in train by past events, but while tobacco remains one of the largest causes of avoidable death and disease, it remains one of the major global public health targets for all countries. REFERENCES 1. 2.

Peto R, Lopez AD, Boreham J et al. Mortality from smoking world-wide. Br Med Bull 1996; 52: 12–21. Gray N (ed). Lung Cancer Prevention; Guidelines for Smoking Control. Geneva: Union Internationale Contre le Cancer, 1977.

3. 4.

5.

6. 7. 8.

9.

Glantz SA, Slade J, Bero LA et al. The Cigarette Papers. Berkeley: University of California Press, 1996. Manley M, Glynn TJ, Shopland D. The Impact of Cigarette Excise Taxes on Smoking Among Children and Adults: Summary Report of a National Cancer Institute Expert Panel. Bethesda MD: National Cancer Institute, 1993. Bjartveit K, Lund KE. The Norwegian Ban on Advertising of Tobacco Products. Has it Worked? Oslo: Norwegian Cancer Society, 1996. Benowitz NL, Henningfield JE. Establishing a nicotine threshold for addiction. N Engl J Med 1994; 331: 123–4. Hoffmann D, Hoffmann I. The changing cigarette, 1950–1995. J Toxicol Environ Health 1997; 50: 307–64. Fischer S, Speigelhalder B, Preussmann R. Tobacco specific nitrosamines in commercial cigarettes; possibilities for reducing exposure. Relevance to Human Cancer of NNitroso Compounds, Tobacco Smoke and Mycotoxins. International Agency for Research on Cancer. Monograph 105. Lyon: 1991 489–93. Gray N, Boyle P, Zatonzki W. Tar concentrations in cigarettes and carcinogen content. Lancet 1998; 352: 787–8.

5

Smoking cessation programs Philip Tønnesen Contents Introduction • Clinical approach • Stages of motivation • Carbon monoxide in expired air • Nicotine replacement therapy • Varenicline • BupropionSR • Other drugs • New drugs • Alternative therapies • Smoking reduction • Special considerations for lung cancer patients who smoke • Weight gain • Conclusions

INTRODUCTION This chapter focuses on the proper use of nicotine replacement therapy (NRT), varenicline, and bupropionSR, golden rules in smoking cessation, predictors of success, and the concept of smoking reduction. It should be remembered that cigarette smoking is an addiction, and for that reason smoking cessation cannot be compared with treatment of other medical conditions. NRT will produce low success rates when used without adjunctive behavioral support; however, since most smokers quit on their own and using over-the-counter (OTC) NRT, even these low success rates will have an important influence on public health. The degree of supportive adjunctive behavioral therapy parallels the actual success rate, while the relative success rate (i.e. the odds ratio between NRT and placebo) remains more or less unchanged at around a factor of two.1 As a preventive tool, smoking cessation is very costeffective. Smoking cessation with NRT or bupropionSR is approximately eight times more cost-effective per saved year compared with 300 medical treatments.2 Also, smoking is the most important etiologic factor in the development of lung cancer, accounting for almost 85% of all lung cancer cases, and has been strongly correlated with other cancers, including oral, laryngeal, and bladder cancer. Around one-third of all cancer deaths are attributed to tobacco.3 Also, tobacco use is a major contributor to chronic obstructive pulmonary disease (COPD) and coronary arteriosclerosis – diseases that often prevent lung cancer patients from undergoing curative surgery.

CLINICAL APPROACH When a health care provider, i.e. a physician, nurse, dentist, or pharmacist, meets with a smoking patient,

he or she has a responsibility to interfere and discourage tobacco use.4,5 The first thing is to ask whether or not the patient is a smoker. Already, by asking, one shows to the patient that one cares about smoking and that smoking might be of importance in relation to health. It is important that the patient’s smoking be handled in a neutral way without anger or condemnation. The smoker should be informed about the risks of smoking, and the information should be individualized for the particular patient.

STAGES OF MOTIVATION Some smokers are contented smokers: they do not consider quitting and do not think about the dangers of smoking. But many smokers would like to quit. Motivation to do so can be regarded as a cyclic process of changes, as described by Prochaska and Goldstein.6 However, these stages do not correlate well with success in quitting. It is much more important for patients with smoking-related diseases such as lung cancer to quit compared with ‘healthy smokers’. Continued smoking in lung cancer patients has a negative effect on the outcome of surgery, chemotherapy, and radiation therapy, and increases the risk of secondary primary lung cancers in long-term survivors. The therapist’s approach to the smoker depends on the motivation to quit. Use of the questions in Table 5.1 is an easy and quick way to classify the motivational stage of the individual smoker and then to apply the right treatment approach. If the smoker wants to quit you should support with advice about NRT and the golden rules of smoking cessation, use NRT, varenicline, or bupropionSR, clinician-provided assistance and skills training, and follow-up visits.7 If the smoker is only interested in cutting down, the smoking reduction concept should be applied. Patients who declare

42 Textbook of Lung Cancer Table 5.1 Assessment of motivation to quit smoking or to reduce

1.

Will you participate in a smoking cessation course now? Answer ‘Yes’: Start smoking cessation ‘No’: Continue to 2 2. Will you try to cut down your daily number of cigarettes now? Answer ‘Yes’: Start smoking reduction ‘No’: Recommend cessation and give brochures 3. How motivated are you to quit on a scale from 0 to 10? (0 = not at all motivated; 10 = extremely motivated) Answer _______ score (0–10) 4. How motivated are you to reduce on a scale from 0 to 10? (0 = not at all motivated; 10 = extremely motivated) Answer _______ score (0–10)

no interest in smoking cessation or reduction should receive brochures and other self-help material about smoking or smoking cessation. More detailed guidelines for smoking cessation have been published by the Agency for Health Care Policy and Research in the USA and by NICE in the UK.8,9 However, there are some basic principles related to successfull smoking cessation that are important for the therapist to consider: smokers must stop smoking completely at quit day (even one or two cigarettes per day during the first one or two weeks of cessation are usually followed by relapse): •

• •

• •

the use of NRT, varenicline and bupropionSR lessens withdrawal symptoms and improves cessation outcome; for lung cancer patients aggressive use of NRT, varenicline, or bupropionSR should be used; follow-up should be arranged to prevent relapse (which is highest during the first three to six weeks, then gradually declines, similarly to other addictions); smoking reduction might be a gateway to smoking cessation in smokers low in motivation to quit; if the patient relapses, he or she should be encouraged to make another attempt to quit later on and then receive retreatment (‘recycling’).

CARBON MONOXIDE IN EXPIRED AIR In most smoking cessation studies, sustained abstinence is used as the outcome measure. It consists of the smoker’s statement of not smoking now and not having smoked since the last visit, together with biochemical verification by carbon monoxide (CO) in expired air. CO measurement is an easy and inexpensive way to verify abstinence biochemically. The half-life of CO varies between four and six hours, and the cut-off value between non-smokers and smokers is usually 10 parts per million (ppm). Most non-smokers attain CO values of 1–4 ppm, and some use a cut-off value of 6 ppm. Subjects exposed to passive smoking might attain values of 6–9 ppm. CO levels are most often measured with a portable CO monitor (Bedfont Monitor, Sittingbourne, UK) in expired air after a 15 s breathhold, with a CO value of less than 6–10 ppm verifying abstinence.10 The result is displayed immediately. Calibrations have to be performed at least every six months using a 50 ppm CO test gas. False-positive values might be observed in subjects with lactose malabsorption. Although an ethanol filter is present, high ethanol concentrations in the breath might interfere with measurements. Drifting of the zero-point might be observed if many smokers are tested consecutively. Without CO monitoring, up to 10% of failures might state that they do not smoke. Plasma, saliva, or urinary cotinine levels are another biochemical way to verify smoking abstinence.

NICOTINE REPLACEMENT THERAPY The rationale for nicotine substitution is as follows. When quitting smoking, the administration of nicotine decreases withdrawal symptoms in the first months, thus allowing the subject to cope with the behavioral and psychologic aspects of smoking (Table 5.2).

Table 5.2 The principle of nicotine replacement therapy (NRT)

• • • • •

Principle: quit cigarettes Use NRT to reduce withdrawal Break the psychologic addiction After two to four months, stop NRT Some might need NRT for longer periods

Smoking cessation programs 43

Withdrawal symptoms (craving for cigarettes, irritability, anxiety, depression, drowsiness, difficulty in concentrating, restlessness, headache, hunger, sleep disturbances) are usually assessed on a four-point scale (0 = not at all; 1 = mild; 2 = moderate; 3 = severe).11,12 Withdrawal symptoms often appear four to eight hours after quitting, peak during the first week (days 3–5), and then gradually decline over the next two to four weeks. Nicotine dependence is measured by the Fagerström test of nicotine dependence (FTND), with a possible scoring of 0–10 (most dependent)13 (Table 5.3). With the nicotine replacement products used today, lower nicotine levels are attained compared with smoking

(i.e. the high peak plasma levels of nicotine reached during smoking are not achieved) (Figure 5.1). Patients are weaned off nicotine replacement products (usually over two to six weeks) when withdrawal symptoms are lessened owing to decreased dependence. The average 12-month success rate reported in most studies is about 15–25%.8,9 Predictors that correlate with a lower success rate are higher nicotine addiction, lower age, no previous quit attempts, previous depression, suffering from COPD and cardiovascular disease, a smoking spouse, and low motivation to quit. Nicotine is the drug of choice to assist smoking cessation. Results reported in a Cochrane meta-analysis

Table 5.3 Fagerström test for nicotine dependence (FTND) Item

1.

How soon after you wake up do you smoke your first cigarette?

2.

Do you find it difficult to refrain from smoking in places where it is forbidden, i.e. in church, at the library, in the cinema, etc.? 3. Which cigarette would you most hate most to give up? 4. How many cigarettes per day do you smoke?

Do you smoke more frequently during the first hours after waking than during the rest of the day? 6. Do you smoke if you are so ill that you are in bed most of the day (or absent from work)?

Plasma nicotine concentrations (ng/ml)

5.

35

Answer

Score

Within 5 min 6–30 min 31–60 min 61 min or more Yes No

3 2 1 0 1 0

The first one in the morning Any others 1–10 11–20 21–30 31 or more Yes No Yes No Total score

1 0 0 1 2 3 1 0 1 0 0–10

Figure 5.1 Plasma nicotine levels during cigarette smoking, nicotine nasal spray (NNS) use, and 4-mg nicotine chewing gum use.

30 25 20

Cigarettes

15

NNS 4-mg gum

10 5 0 8

9

12

16

20

Time (hours)

24

4

8

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of 105 trials with 39 503 subjects, who received various forms of NRT (gum, patch, spray, inhaler, and sublingual/lozenge), indicated that NRT almost doubled long-term (6–12 months) quit rates.14 The odds ratio for success of NRT compared with controls was 1.8 (95% confidence interval, CI, 1.7–1.9). The odds ratios for the different nicotine replacement products were 1.6 for gum, 1.8 for patch, 2.4 for nasal spray, 2.1 for inhaler, and 2.1 for sublingual/lozenge (Table 5.4). Overall, there was no statistical difference between the different forms of NRT and this has also been found in comparative studies. The nicotine products described above are self-dosing systems to be used ad libitum, in contrast to the patch, which ‘infuses’ about 1 mg of nicotine per hour at a constant rate. There are six different formulations of nicotine replacement products (Table 5.5) and the determination of the most appropriate product should be according to patient preference, cost, nicotine dependence, and number of daily cigarettes (Tables 5.6–5.9).

Nicotine chewing gum Gum users should only chew a piece five to ten times until they can taste the nicotine, then let the gum rest in the cheek for a few minutes, and then chew again to expose a new surface of the gum. Free nicotine can then be absorbed and reduce side-effects due to swallowed nicotine. The gum can be chewed for about 20–30 minutes. About 0.8–1.2 mg of nicotine is absorbed from a piece of 2-mg nicotine gum, and 1.2–1.5 mg of nicotine from a 4-mg piece15 (Table 5.5). With use of nicotine gum throughout the day, blood levels of one-third (for 2-mg gum) and two-thirds (for 4-mg gum) of the nicotine obtained through smoking are achieved.16,17 A basic advantage of gum is the possibility of self-titrating the dose, in contrast to the patch, which delivers a fixed dose. Thus it is possible to use a piece of

gum whenever it is wanted or needed during the day. The principal disadvantage of gum use is potential

underdosing, which might explain the lack of effect in several trials. The approximate dose equivalent for most nicotine patches is approximately 20 pieces of the 2-mg

Table 5.5 NRT formulations

Gum 2 and 4 mg content: 0.8–1.2 mg and 1.2–1.5 mg absorbed, respectively Patch 15 mg/16 h; 21 mg/24 h Inhaler 10 mg in one container: 4–5 mg released (2–3 mg in clinical use) Nasal spray 0.5 mg/dose in each nostril Sublingual tablet 2 mg content: 0.8–1.2 mg absorbed Lozenge 1 mg and 2 mg content: 0.5 and 0.8–1.2 mg absorbed

Table 5.6 NRT use: 1

1–9 cigarettes/day (not-evidence based) • 2-mg gum • Inhaler • 1-mg lozenge 7–9 cigarettes/day • As above, or • Patch 10-mg/16 h or 7-mg/24 h

Table 5.4 Efficacy of NRT

Table 5.7 NRT use: 2

• • •

10–20 cigarettes/day • Patch: 15-mg/16 h or 14-mg/24 h • Gum 2- or 4-mg • Inhaler • 2-mg lozenge or 2-mg sublingual

• • • • •

Meta-analysis controlled trials Success rates sustained for one year Odds ratio 1.77 (95% CI 1.67–1.89) Gum: 1.66 Patch: 1.81 Nasal spray: 2.35 Inhaler: 2.14 Sublingual/lozenge: 2.05

15–20 cigarettes • As above, or • NNS

Smoking cessation programs 45

Table 5.8 NRT use: 3

21+ cigarettes/day • Patch: 25-mg/16 h or 21-mg/24 h • Gum: 4-mg • NNS • Inhaler • Sublingual 2-mg or lozenge 2-mg • Gum as rescue in relapse situations • NRT as long-term use if needed • Combination of patch and one of the other NRTs • NRT in combination with bupropionSR

Table 5.9 NRT use: 4

• • • • •

Use of NRT in smokers as withdrawal suppressor Meetings, workplaces, travel Few hours: gum, inhaler 6 or more hours: gum, inhaler, patch Instruct smoker to try a piece of gum/inhaler before travel starts

Table 5.10 Varenicline use

10+ cigarettes/day • Varenicline 0.5 mg in morning days 1–3; then 0.5 mg b.i.d. days 4–7 • Quit smoking after 1 (–2) week • Varenicline 1 mg b.i.d. • Duration: 12 weeks • In quitters after 12 weeks eventually continue with varenicline up to 6 months • Side-effects: mild nausea (30%), vomiting (2%) • Contraindications: severe renal failure

gum, whereas the mean number of pieces of gum consumed daily is only around five to six in most studies. Thus underdosing is a plausible explanation for lack of efficacy in several studies.18,19 From these observations, it would be logical to attempt to raise the consumed dose either by increasing the number of pieces of gum chewed or by using the higher-dose (4-mg) gum. In four studies comparing the 4- and 2-mg gums, the 4-mg gum was superior to the 2-mg gum for short-term outcome. Another way to

increase the amount of consumed gum might be to administer it in fixed-dosage schedules as shown by Killen et al.20 Side-effects of gum consist mainly of mild, transient, local symptoms in the mouth, throat, and stomach due to swallowed nicotine (i.e. nausea, vomiting, indigestion, and hiccups). After adequate instruction, most smokers can learn to use the gum properly. However, without instruction many will discontinue use or underdose themselves. In the Lung Health Study, among 3094 smokers who were followed for five years, the use of the 2-mg gum appeared safe and did not produce cardiovascular problems or other adverse events, even in subjects who continued to smoke and still used nicotine gum.21 It is suggested that smokers be instructed to stop smoking completely, use the nicotine gum on a fixed schedule (i.e. every hour, from early morning, for at least 8–10 hours), and to use extra pieces of gum whenever needed. The optimal duration of treatment is not known; however, in most studies, the gum has been used for at least 6–12 weeks and up to one year. Individualization of treatment duration is recommended. Nicotine transdermal patch The nicotine patch is a fixed nicotine delivery system that releases about 1 mg of nicotine per hour for 16 hours (daytime patch) or for 24 hours (24-hour patch). Nicotine substitution is about 50% of the smoking level (21-mg patch/24 h and 15-mg patch/16 h) (Table 5.5). The nicotine curve attained in plasma with patches is flat, without the high peaks attained by cigarette smoking. It is much easier to administer the patch and to use it compared with gum, but it is not possible to self-titrate.22 The recommended treatment duration is 8–12 weeks. In a multicenter smoking cessation trial from the USA, examining the effect of 0, 7-mg, 14-mg, and 21-mg nicotine patches, a dose–response effect of increasing nicotine dosages was reported.23 Two large placebo-controlled trials with 600 and 1686 smokers have been published.24,25 The one-year success rate was 9.3% in the active patch group versus 5.0% in the placebo patch group in the first study,24 and 9.0% versus 6.3% in the other study.25 Among 19 studies examining long-term (i.e. 6–12 months) smoking cessation success, 10 showed a significant outcome in favor of the nicotine patch.22 The pooled success rate was 15.8% for active patches versus 8.8% for placebos (odds ratio 1.98; 95% CI 1.70–2.30).

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Side-effects are mainly mild local skin irritation, occurring in 10–20% of subjects. In only 1.5–2.0% of subjects was the patch terminated owing to more persistent and severe skin irritation at the patch location.22 Because of its ease of use, the patch may be the first choice of nicotine delivery system today. Transdermal nicotine replacement does increase success in smoking cessation with minimal adjunctive support. Nicotine inhaler An inhaler consists of a mouthpiece and a plastic tube with a porous plug impregnated with nicotine, which releases nicotine vapor when air is drawn through the plug. Most of the nicotine is absorbed through the mouth and throat. Each inhaler contains 10 mg of nicotine (Table 5.5). In clinical use, each inhaler releases approximately 2–3 mg of nicotine, and the number of inhalers used daily averages five or six. Thus, nicotine levels comparable to those found during use of the 2-mg nicotine gum are attainable (i.e. relatively low concentrations). Few controlled trials have been conducted with nicotine inhalers. The efficacy and safety of the nicotine inhaler were examined in a double-blind, clinical, smoking cessation trial.26 The first published study was a one-year, randomized, double-blind, placebo-controlled trial that enrolled 286 smokers. The success rates for smoking cessation were 15% and 5% at 12 months (p < 0.001) for active and placebo, respectively. The mean nicotine substitution based on determinations after one to two weeks of therapy was 38–43% of smoking levels. The treatment was well accepted, and no serious adverse events were reported. Three other studies have confirmed the above finding, with odds ratios in favor of active treatment of 1.6, 2.2, and 1.6.27 The inhaler may replace some of the habit patterns associated with smoking (e.g. oral and handling reinforcement), along with providing nicotine replacement. At least four inhalers should be used per day, the optimal number being 4–10 per day and the duration of use three months, with another 3–9 months of use and downtitration if needed. With rapid and frequent puffing, it is possible to increase the dose. Nicotine nasal spray The nicotine nasal spray (NNS) consists of a multidose, hand-driven, pump spray with nicotine solution. Each puff contains 0.5 mg nicotine; thus a 1-mg dose is delivered if both nostrils are sprayed as recommended (Table 5.5). The NNS is a strong and rapid means of delivering nicotine into the body with a pharmacokinetic

profile closer to cigarettes. After a single dose of 1 mg nicotine, the peak level is reached within 5–10 minutes, with average plasma trough levels of 16 ng/ml. Three published studies with the NNS indicate that the one-year success rates for active NNS versus placebo, respectively, were 26% and 10%, 27% and 15%, and 27% and 17%.28,29 This strong spray induces localized side-effects, such as sneezing, nasal secretion and irritation, and congestion, watery eyes, and coughing. Up to 5% of subjects rate these side-effects as unacceptable; however, most symptoms decrease within a few days after the spray is initiated. Highly nicotine-dependent smokers might be the target group for this delivery mode of nicotine. The NNS should be used for three months, but has been used for up to one year in some studies. The dose is from 10 to 40 puffs in each nostril per day. Nicotine sublingual tablet/lozenge The 2-mg sublingual tablet should be placed under the tongue, where it will disintegrate within 20 minutes. The 1-mg and 2-mg lozenges should be sucked at until a strong taste appears, they should then rest in the cheek for a few minutes and then the cycle is repeated for 15–20 minutes. The nicotine released from the tablet will be absorbed through the oral mucous membrane and the dose delivered is comparable with the 2-mg nicotine chewing gum.30 Side-effects are similar to those from the nicotine gum. Many subjects with dentures who cannot use nicotine gum can use tablets or lozenges. The tablet/lozenge should be used for three months, but duration of treatment should be individualized for up to one year or longer. One tablet per hour is the recommended dosage up to 20/day, with a maximum dose up to 40 tablets/day in highly dependent smokers. Combination of two different NRTs Relatively few studies have been published about the combination of two NRT products. A short-term increase in success has been observed in some, and a trend towards a statistically significant 12-month increase has been found in meta-analysis.14 A dose–response effect has been observed with both the nicotine gum and patch. Even 22- and 44-mg patches have been tested with promising results after four weeks of treatment, i.e. success rates of 45% and 68%. In two studies the degree of nicotine substitution was compared to outcome and in both higher success rates were found with increasing degree of substitution.

Smoking cessation programs 47

In the CEASE study comprising 3575 subjects, a higher success rate was achieved with 25-mg 16-hour patches compared with 15-mg nicotine patches.31 Overall, in clinical use the combinations of different NRT administration forms seem safe with few sideeffects. Also, concomitant use of NRT and cigarette smoking seems safe, with nicotine concentrations similar to those found during normal cigarette smoking. VARENICLINE Varenicline affects the central nicotine receptors by binding to the nicotine receptor as an agonist with some antagonist action. This means that varenicline mimicks the effect of nicotine, but also prevents the pleasure from cigarette smoking by preventing nicotine from binding to the receptor. In two studies with 1025 and 1027 smokers with similar design, varenicline 1 mg bid was compared with bupropionSR 150 mg bid versus placebo for three months.32,33 The quit rate after 1 year was 22% and 23% for varenicline, 16.4% and 15% for bupropionSR, and 8.4% and 10.3% for placebo, i.e. there were significantly higher quit rates for varenicline versus placebo and bupropionSR. A relapse prevention study reported that, in subjects who had quit after 3 months, prolongation of varenicline use for another three months resulted in a higher quit rate after one year.34 The major side-effect was nausea in approximately 30% of cases, with 2–3% discontinuing the drug due to nausea and vomiting. However, in most subjects the nausea was not a major problem. No drug interactions have been found, and no significant contraindications have been reported, except severe renal failure. Varenicline has no effect on post-cessation weight gain. Overall, varenicline is a new, effective, and safe agent for smoking cessation. Also, varenicline tends to be more effective than bupropionSR. Varenicline should be considered a first-line drug in lung cancer patients. The dosing should be varenicline 0.5 mg a.m. for 3 days, 0.5 mg bid for another 3 days, then quit cigarettes from day 7 and continue with 1 mg varenicline bid for 12 weeks and, if needed, up to six months.

of 19 placebo-controlled studies reported a doubling of quit rates with an odds ratio of 2.06 (95% CI 1.8–2.4) in favor of bupropionSR.35 The recommended dosing for bupropionSR is 150 mg a.m. for one week prior to the quit date, in order to establish adequate blood levels. Therapy should then continue with 150 mg bid for 7–12 weeks. Common adverse events from bupropionSR are insomnia (up to 40%) and dry mouth. These sideeffects usually decline during the first week of therapy. In clinical trials the treatment was stopped due to adverse events in 10–12% of subjects. The most serious adverse event was epileptic seizures, which were reported in 0.1% of patients, and allergic reactions (1–2%), with 0.1% cases of serious hypersensitivity.35,36 The formulation is slow release to prevent high peak concentrations as seizures are concentration-dependent. BupropionSR is contraindicated in individuals with an increased risk of seizures (e.g. epilepsy, earlier head trauma, anorexia nervosa). A reduced dose – that is, one tablet daily – is recommended in patients with severe liver impairment. As bupropionSR is metabolized in the liver, interactions occur with several drugs. Similarly, it is important not to increase the dose above 300 mg, and to administer the daily dose in divided form, with an interval of at least eight hours. The last dose should not be taken later than 6 p.m. if insomnia is a problem. Post-cessation weight gain is reduced by 2–3 kg during the drug treatment period. There are few studies comparing bupropionSR with NRT or looking at the combination effect; however, the combination seems safe and is recommended for hard-core smokers such as lung cancer patients. BupropionSR is of similar efficacy to NRT and is generally well tolerated in smoking cessation. As bupropionSR has a more severe side-effect profile, more contraindications, and is only available on prescription, I regard NRT as first-line medication and bupropionSR as a second-line drug, but this is a matter of personal judgment and in most guidelines bupropionSR is a first-line medication. The dosing should be bupropionSR 150 mg a.m. for 6 days, then quit cigarettes from day 7 and continue with 150 mg bid for 7–12 weeks and, if needed, up to six months (see Table 5.11).

BUPROPIONSR OTHER DRUGS BupropionSR, an amino-ketone, is an antidepressant that differs from tricyclic antidepressants and serotonin reuptake inhibitors, and the effect on smoking is not coupled to the antidepressive effect per se. A meta-analysis

Nortriptyline, a tricyclic antidepressant, has been shown to be as effective as NRT and bupropionSR in smoking cessation. A meta-analysis of four trials found an odds

48 Textbook of Lung Cancer Table 5.11 BupropionSR use

10+ cigarettes/day • BupropionSR 150 mg in the morning for 7 days • Quit smoking after 7 days • Increase dose: bupropionSR 150 mg b.i.d. • Duration: 7–12 weeks • Side-effects: sleep disturbances, seizures in 1:2000 • Contraindications: epilepsy, increased risk of seizures, impaired liver function

It might be used as a secondary drug, especially in smokers afraid of or not accepting weight gain. Rimonabant has been marketed as a weight-reducing agent due to the low efficacy in smoking cessation. Several nicotine vaccines are under development. The principle is to produce antibodies in the blood that prevent most of the inhaled nicotine from cigarettes from reaching the brain. Phase II studies have found that it is possible to induce a long-term antibody level in humans with a safe vaccine and that high antibody response is associated with smoking cessation.40

ALTERNATIVE THERAPIES ratio of 2.8 (1.7–4.6) for one-year quit rates for nortriptyline versus placebo at a dose of 50–75 mg daily.37 There are contraindications, common anticholinergic side-effects, and particularly cardiac conduction disturbances and a decrease in orthostatic blood pressure. However, at the relatively low dose used for smoking cessation, nortriptyline seems to be relatively well tolerated and is a second-line agent or even first-line agent, especially in countries that cannot afford the more expensive first-line drugs or where they are not marketed. Several other antidepressants including selective serotonin re-uptake inhibitors have not been found to be effective in smoking cessation, e.g. doxepin, fluoxetine, sertraline, moclobemide, and venlafaxine. Clonidine, an α2-noradrenergic agonist, has been used as a smoking cessation agent. Six studies were included in a meta-analysis comprising 722 subjects, and the odds ratio of success with clonidine versus placebo was 1.89 (95% CI 1.30–2.74).38 However, a high incidence of adverse effects (median 71%) occurred (e.g. dry mouth, sedation, dizziness, and symptomatic postural hypotension). In my opinion – due to the high incidence of adverse events – clonidine is an obsolete drug in this area.

NEW DRUGS Rimonabant is a cannabinoid type 1 receptor antagonist with a central action and has been tested in smoking cessation trials. Preliminary results showed an increased three month quit rate with rimonabant, with relatively low absolute abstinence rates.39 Rimonabant more or less prevents post-cessation weight gain; however, when the drug is ceased weight increases. The role of rimonabant in smoking cessation has to be defined.

Other ‘popular’ interventions often used are acupuncture and hypnosis. However, there is no evidence to support an effect from hypnosis or other alternative therapies. A meta-analysis comparing active versus control acupuncture found that acupuncture was no more effective than placebo.41 One study reported no effect for laser therapy in 320 adolescents.42

SMOKING REDUCTION Many smokers would prefer to reduce the number of cigarettes smoked daily instead of quitting completely. The aim of smoking reduction is to widen access to cessation by including smokers not currently able or willing to stop abruptly, wanting to reduce smoking, or unable or unwilling to quit. As shown below, by the concept of smoking reduction it is possible to recruit a new segment of smokers who are not interested in abrupt cessation. The reduction process should be looked at as a gateway to complete cessation. The definition of smoking reduction is a decrease in the number of cigarettes (or tobacco) smoked daily. A 50% reduction or more in daily cigarettes has been chosen arbitrarily in most studies.43,44 Several randomized controlled trials have been published. In eight studies, two using nicotine inhalers and six using nicotine chewing gum for half to one year, comprising 2424 smokers, a reduction (>50%) was reported in 15.9% of smokers using nicotine products compared with a reduction in 6.7% of placebo users.45 Surprisingly, after one year a smoking cessation rate of 8.4% was found among nicotine users versus 4.1% in placebo users. A reduction of more than 50% after 3–4 months had a strong predictive value for quitting at one year. Also, participation in reduction

Smoking cessation programs 49

trials increased the motivation to quit smoking, thus not undermining the motivation to stop smoking completely. Another way to attain smoking reduction and reduce the harm of smoking could be through tobacco product modification.46 For the group of smokers not motivated to quit smoking a less hazardous cigarette might be an advantage. Also, smokeless tobacco (chewing tobacco and snuff) might be an alternative with tobacco smoking, with fewer health risks compared with smoking.47 Epidemiologic studies in Sweden have found much less harm in snuff users compared with cigarette smokers.48 The smoking reduction concept should be offered to smokers who are not motivated to quit. They should be prescribed NRT – nicotine gum or inhaler – for three months and recommended to reduce the number of cigarettes by at least 50% during the first 1–2 weeks and then to try to reduce further. If the smoker has not reduced by more than 50% after three months, NRT should be stopped as the chance of quitting then is low. In smokers who have reduced by more than 50%, NRT should be continued for up to one year, and after six months they should be recommended to try to stop smoking completely. In summary, smoking reduction seems to have a role for smokers not motivated or able to quit, as a gateway to complete cessation. There is limited evidence that smoking reduction is followed by an improvement in health, in contrast to the use of smokeless tobacco products.

SPECIAL CONSIDERATIONS FOR LUNG CANCER PATIENTS WHO SMOKE In this group of patients as many as 80% quit smoking during the time of diagnosis.49 However, up to 50% of patients undergoing curative surgery for lung cancer relapse and smoke after five years, thus increasing the risk of a secondary primary lung cancer.50,51 In healthy smokers a high relapse rate is observed during the first month after quit day, in contrast to cancer patients where most relapses occur between one and six months after quit day.52,53 An increasing proportion of lung cancer patients undergo chemotherapy and this proportion will probably further increase during the next decade due to increased public focus on this disease. Thus, in the future most patients will undergo treatment with surgery and/or chemotherapy. The importance of smoking cessation is due to a decreased complication rate after

surgery and during chemotherapy and radiation therapy if the patient has stopped smoking. The period of diagnosis and therapy might elicit depressive reactions and put a heavy strain on the patient’s and family’s mental and social situations. Many family members of lung cancer patients are often smokers and do not quit spontaneously during this period.54 It might also be that lung cancer patients are more nicotine dependent.55 Overall, this calls for a more intensive and aggressive effort to get these patients to successfully quit smoking. A nurse-managed program reported an abstinence rate of 40% after six weeks.54 A combination of nicotine patch with another NRT product should be the rule, and also a longer duration of treatment with the possibility to continue long term with NRT. A combination of NRT and bupropionSR might also be an option. However, as many of these smokers have tried NRT previously, varenicline might be the right option for these dependent smokers. Scheduled visits with smoking cessation counseling and support are important, to be combined eventually with telephone calls. In healthy smokers higher quit rates have been obtained if spouses are also enrolled in the same program and quit smoking, and this might also prove to be the case for lung cancer patients. For the small fraction of lung cancer patients with the lowest performance status, where only supportive therapy is prescribed and who have an expected short survival time, I would not actively suggest smoking cessation. The clinics involved with the diagnostics and therapy of lung cancer should be able to cover smoking cessation, and the health-care workers should have an adequate knowledge about smoking cessation.52 It is important that a specific budget is allocated to each clinic for a smoking cessation service.

WEIGHT GAIN A weight gain of 3 to 6 kg for abstainers after one year is found in most studies.56,57 In 10% of males and 13% of females the weight increase is more than 14 kg, i.e. they are ‘supergainers’. About half of the participants are afraid of gaining weight and it may be a more significant problem for females. Weight gain can be regarded as a withdrawal symptom due to increased hunger and increased caloric intake. NRT products are only partially able to reduce the post-cessation weight gain while bupropionSR has a slightly greater effect, i.e. a reduction in post-cessation weight gain of 2–3 kg.57

50 Textbook of Lung Cancer

For lung cancer patients the increase in weight might be an advantage if they are underweight. The increase in appetite might also be an advantage for patients with decreased appetite.

CONCLUSIONS In summary, NRT, varenicline, and bupropionSR almost double the one-year cessation outcome, and, combined with counseling and behavioral strategies, are important adjuncts for maintaining long-term smoking cessation. Nicotine gum, patch, and inhaler are first line drugs, while NNS nasal spray is for the more heavily dependent smokers. The patch might not be the first choice for heavily dependent smokers. The duration of NRT treatment is approximately three months, with individual variations. NRT is a very cost-effective treatment compared with several other medical treatments, and should be much more widely implemented in the future. If the smoker has failed using NRT, varenicline or bupropionSR is the choice. As lung cancer patients might be more nicotinedependent and have more difficulty in stopping smoking, a more aggressive therapeutic approach should be used, i.e. higher doses of NRT, a combination of two NRT formulations, varenicline, bupropionSR plus NRT, a longer duration of therapy (6–12 months), and more support visits. Family members who smoke should also be enrolled in a cessation program. Most lung cancer patients have used NRT previously, varenicline seems to be the drug of choice as it seems more effective than bupropionSR, with fewer adverse effects and almost no contraindications or interactions. Also, varenicline tends to be more effective when compared with bupropionSR. Physicians and other health-care providers have an obligation to discourage tobacco use in their patients and to deliver up-to-date assistance in smoking cessation.

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3. Peto R, Lopez AD, Boreham J et al. Mortality from tobacco in developed countries 1950–2000. Oxford: Oxford University Press, 1994. 4. World Health Organisation (WHO). European partnership to reduce tobacco dependence: WHO evidence based recommendations on the treatment of tobacco dependence. Geneva: WHO, 2001. 5. IASLC Workshop. Prevention and early detection of lung cancer. Clinical aspects. Proceedings. Elsinore, Denmark, 1996. 6. Prochaska JO, Goldstein MG. Process of smoking cessation. Implications for clinicians. Clin Chest Med 1991; 12: 727–35. 7. American College of Chest Physicians, American Thoracic Society, Asia Pacific Society of Respirology, Canadian Thoracic Society, European Respiratory Society International Union Against Tuberculosis and Lung Diseases. Smoking and health: a physician’s responsibility. A statement of the joint committee on smoking and health. Eur Respir J 1995; 8: 1808–11. 8. USDHHS. Tobacco and the Clinician: Interventions for Medical and Dental Practice. NCI 94-3693. Rockville, MD: US Department of Health and Human Services, Public Health Service, National Institutes of Health, 1994. 9. National Institute for Clinical Excellence (NICE). Guidance on the use of nicotine replacement therapy (NRT) and bupropionSR for smoking cessation. National Institute for Clinical Excellence Technology Appraisal Guidance No 39, 2002. Available from URL:www.nice.org.uk. 10. Jarvis MJ, Russell MA, Saloojee Y. Expired air carbon monoxide: a simple breath test of tobacco smoke intake. BMJ 1980; 281: 484–5. 11. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders–IV. Washington, DC: APA, 1994. 12. Hughes JR, Gust SW, Skoog K et al. Symptoms of tobacco withdrawal. A replication and extension. Arch Gen Psychiatry 1991; 48: 52–9. 13. Fagerström KO, Heatherton TF, Kozlowski LT. Nicotine addiction and its assessment. Ear Nose Throat J 1991; 69: 763–8. 14. Silagy C, Lancaster T, Stead L et al. Nicotine replacement therapy for smoking cessation. Cochrane Database Syst Rev 2004; 3: CD000146. 15. McNabb ME, Ebert RV, McCusker K. Plasma nicotine levels produced by chewing nicotine gum. JAMA 1982; 248: 865–8. 16. McNabb ME. Chewing nicotine gum for 3 months: What happens to plasma nicotine levels? Can Med Assoc J 1984; 131: 589–92. 17. Tønnesen P, Fryd V, Hansen M et al. Two and four mg nicotine chewing gum and group counseling in smoking cessation: an open, randomized, controlled trial with a 22 month follow-up. Addict Behav 1988; 13: 17–27. 18. Tønnesen P, Fryd V, Hansen M et al. Effect of nicotine chewing gum in combination with group counseling on the cessation of smoking. N Engl J Med 1988; 318: 15–18. 19. Puska P, Bjorkqvist S, Koskela K. Nicotine containing chewing gum in smoking cessation: a double-blind trial with half year follow-up. Addict Behav 1979; 4: 141–6.

Smoking cessation programs 51 20. Killen JD, Fortmann SP, Newman B, Varady A. Evaluation of a treatment approach combining nicotine gum with selfguided behavioral treatments for smoking relapse prevention. J Consult Clin Psychol 1990; 58: 85–92. 21. Murray RP, Bailey WC, Daniels K et al. Safety of nicotine polacrilex gum used by 3,094 participants in the Lung Health Study. Chest 1996; 109: 438–45. 22. Fagerström KO, Säwe U, Tønnesen P. Therapeutic use of nicotine patches: efficacy and safety. J Smok Relat Dis 1992; 3: 247–61. 23. Transdermal Nicotine Study Group. Transdermal nicotine for smoking cessation. JAMA 1991; 22: 3133–8. 24. Russell MAH, Stableton JA, Feyerabend C et al. Targeting heavy smokers in general practice: randomized controlled trial of transdermal nicotine patches. BMJ 1993; 306: 1308–12. 25. Imperial Cancer Research Fund General Practice Research Group. Effectiveness of a nicotine patch in helping people to stop smoking: results of a randomized trial in general practice. BMJ 1993; 306: 1304–8. 26. Tønnesen P, Nørregaard J, Mikkelsen K et al. A double-blind trial of a nicotine inhaler for smoking cessation. JAMA 1993; 269: 1268–71. 27. Schneider NG, Olmstead R, Nilsson F et al. Efficacy of a nicotine inhaler in smoking cessation: a double-blind, placebocontrolled trial. Addiction 1996; 91: 1293–306. 28. Sutherland G, Stapleton JA, Russell MAH et al. Randomised controlled trial of a nasal nicotine spray in smoking cessation. Lancet 1992; 340: 324–9. 29. Blondal T, Franzon M, Westin A et al. Controlled trial of nicotine nasal spray with long term follow-up. ARRD 1993; 147: A806. 30. Wallström M, Nilsson F, Hirch JM. A randomized, doubleblind, placebo-controlled clinical evaluation of a nicotine sublingual tablet in smoking cessation. Addiction 2000; 95: 1161–71. 31. Tønnesen P, Paoletti P, Gustavsson G et al. Higher dosage nicotine patches increase one-year smoking cessation rates: results from the European CEASE trial. Eur Respir J 1999; 13: 238–46. 32. Gonzales D, Rennard SI, Nides M et al. Varenicline, an α4, β2 nicotinic acetylcholine receptor partial agonist, vs sustainedrelease bupropionSR and placebo for smoking cessation. JAMA 2006; 296: 47–55. 33. Jorgenby DE, Hays T, Rigotti NA et al. Efficacy of varenicline, an α4, β2 nicotinic acetylcholine receptor partial agonist, vs placebo or sustained-release bupropionSR for smoking cessation. JAMA 2006; 296: 56–63. 34. Tonstad S, Tønnesen P, Hajek P et al. Effect of maintenance therapy with varenicline on smoking cessation. JAMA 2006; 296: 64–71. 35. Hughes JR, Stead LF, Lancaster T. Antidepressants for smoking cessation. Cochrane Database Syst Rev 2004; 4: CD000031. 36. Tønnesen P, Tonstad S, Hjalmarson A et al. A multicentre, randomised, double-blind, placebo-controlled, 1-year study of bupropionSR for smoking cessation. J Intern Med 2003; 254: 184–92. 37. Wagena EJ, Knipschild P, Zeegers MPA. Should nortriptyline be used as a first-line aid to help smokers quit? Results from a

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systematic review and meta-analysis. Addiction 2005; 100: 317–26. Glourlay SG, Stead LF, Benowitz NL. Meta-analysis of clonidine for smoking cessation. Cochrane Database Syst Rev 2004; 3: CD000058. Cox SL. Rimonabant hydrochloride: an investigational agent for the management of cardiovascular risk factors. Drugs Today (Barc) 2005; 41: 499–508. Hatsukami DK, Rennard S, Jorenby D et al. Safety and immunogenicity of a nicotine conjugate vaccine in current smokers. Clin Pharmacol Ther 2005; 78: 456–67. White AR, Rampes H, Earnst E. Acupuncture for smoking cessation. Cochrane Database Syst Rev 2002; 2: CD000009. Yiming C, Changxin Z, Ung WS et al. Laser acupunture for adolescent smokers – a randomised, double-blind controlled trial. Am J Chin Med 2000; 28: 443–9. Bolliger CT, Zellweger JP, Danielsson T et al. Smoking reduction with oral nicotine inhalers: double blind, randomised clinical trial of efficacy and safety. BMJ 2000; 321: 329–33. Wennike P, Danielsson T, Landfeldt T et al. Smoking reduction promotes smoking cessation: results from a double blind, randomized, placebo-controlled trial of nicotine gum with 2-year follow-up. Addiction 2003; 98: 1395–402. Tonnesen P, Danielsson T. Cutting down smoking then stopping with nicotine replacement therapy: an innovative approach to smoking cessation. Thorax 2005; 60 (Suppl II): ii36. Bates C, McNeill A, Jarvis M, Gray N. The future of tobacco product regulation and labelling in Europe: implications for the forthcoming European Union directive. Tob Control 1999; 8: 225–35. Kozlowski LT, O’Connor RJ, Edwards BQ, Flaherty BP. Most smokeless tobacco use is not a casual gateway to cigarettes: using order of product use to evaluate causation in a national US sample. Addiction 2003; 98: 1077–85. Henley SJ, Thun MJ, Connell C, Calle EE. Two large prospective studies of mortality among men who use snuff or chewing tobacco. Cancer Causes Control 2005; 16: 347–58. Sanderson Cox L, Sloan JA, Patten CA et al. Smoking behavior of 226 patients with diagnosis of stage IIIA/IIIB non-small cell lung cancer. Psychooncology 2002; 11: 472–8. Richardson GE, Tucker MA, Venzon DJ et al. Smoking cessation after successful treatment of small-cell lung cancer is associated with fewer smoking-related second primary cancers. Ann Intern Med 1993; 119: 383–90. Kawahara M, Ushijima S, Kamimori T et al. Second primary tumours in more than 2-year disease-free survivors of small-cell lung cancer in Japan: the role of smoking cessation. Br J Cancer 1998; 78: 409–12. Gritz ER. Facilating smoking cessation in cancer patients. Tobacco Control 2000; 9 (Suppl I): i50. Wewers ME, Jenkins L, Mignery T. A nurse-managed smoking cessation intervention during diagnostic testing in lung cancer. Oncol Nurs Forum 1997; 24: 1419–22. Solak ZA, Goksel T, Telli CG, Erdinc E. Success of a smoking cessation program among smoking relatives of patients with serious smoking-related pulmonary disorders. Eur Addict Res 2005; 11: 57–61.

52 Textbook of Lung Cancer 55. Schnoll RA, Rothman RL, Newman H et al. Characteristics of cancer patients entering a smoking cessation program and correlates of quit motivation: implications for the development of tobacco control programs for cancer patients. Psychooncology 2004; 13: 346–58. 56. Klesges RC, Winders SE, Meyers AW. How much weight gain occurs following smoking cessation? A comparison of weight

gain using both continuous and point prevalence abstainers. J Consult Clin Psychol 1997; 65: 286–91. 57. Hays JT, Hurt RD, Rigelli NA. Sustained-release bupropionSR for pharmacological relapse prevention after smoking cessation, a randomised, controlled trial. Ann Intern Med 2001; 135: 423–33.

6

Current status of lung cancer screening James L Mulshine Contents Introduction • Current evidence • Technical innovations with CT imaging • Recommendations from professional societies • Recent developments • Conclusion

INTRODUCTION Lung cancer screening is the crucible where providing an expensive new service with the potential for harm in vast numbers of variably at-risk individuals collides with the consequences of the world’s most lethal cancer. With over 160 000 annual deaths, lung cancer accounts for 30% of cancer deaths in the USA.1 Regional or distant metastatic spread is evident in at least threequarters of lung cancer cases at time of initial diagnosis resulting in a 5-year survival rate of 15%. For surgically resected cancer, the 5-year survival rate exceeds 60%. By comparison, localized breast and prostate cancer are detected at rates of 63 and 82%, so correspondingly their 5-year survival rates are much better at 87 and 98%, respectively. For women, there has been a 600% increase in the frequency in lung cancer over the last eighty years, and lung cancer death rates in United States women are the least favorable in the world.2 Unlike cardiovascular disease, the risk of developing lung cancer remains elevated after smoking cessation.3–5 Lung cancers are being diagnosed at least as frequently in the over 45 million former smokers as in current smokers,3 and smoking cessation strategies are of no utility in the growing cohort of former smokers. The progress in cardiovascular disease has not been matched in lung cancer outcomes, so this cancer has recently emerged as the dominant cause of death in tobaccoexposed individuals.6 Tobacco-related diseases are the leading cause of premature death and account for half of health-care costs in our society, so better approaches to lung cancer management are critical.7 Promising reports with high-resolution computed tomography (CT) detection have renewed interest in early lung cancer screening.4,8–11 No major lung cancer screening trial has been completed here in decades and the recent United States Preventive Services Task Force (USPSTF) analysis acknowledges the methodologic limitations of the previous chest X-ray screening trials.12–14 Lingering debate about those earlier trials has fostered

concern about CT-based lung cancer detection being not only prohibitively expensive but possibly dangerous.15–17 Against this charged back drop, it is timely to review the status of early lung cancer detection.

CURRENT EVIDENCE A number of CT screening pilot studies have been reported over the last few years (Table 6.1). While there are different eligibility criteria and case work-up approaches, these single-arm studies have been consistent for several critical parameters. Frequency of stage I detection with CT screening is about 80%, which is considerably higher than the national experience of 17%.1 This published experience is too recent to have long-term clinical outcomes except for a recently presented Japanese series. From 1975–1993, the Anti-lung Cancer Association performed 26 338 screening chest X-rays,18 and in the detected cases 42% were stage I lung cancer with an average primary size of 3 cm and 33% were stage III/IV. During 1993, this group began using CT and, by 2002, 15 342 scans had been performed. With CT screening, 78% of the detected cases were stage I with a mean diameter of 1.5 cm and the rate of detection for stage III/VI disease had decreased to 14%. With this transition, the overall 5-year survival improved from 49% with chest X-ray-detected cases to 84% with CT-detected cases. This experience is consistent with the early reports from the International-Early Lung Cancer Action Project (I-ELCAP), whose screening experience with current and former smokers was presented with prevalence evaluation of over 26 000 subjects and follow-up incidence data from 19 700 subjects.19,20 The critical endpoint of a randomized trial is significant cancer-related mortality reduction in the screened population compared to a control population. The randomized trial design addresses the potentially confounding influence of overdiagnosis. The term

54 Textbook of Lung Cancer Table 6.1 Distillation of the pilot CT screening results for non-small cell lung cancer No of subjects

Prevalence cohorts8,37,38,67,71 Incidence cohorts33,37,38,67,71

Number of CT-detected lung cancers tumors

Mean size of primary (mm)

Percent stage I cancers

13 122

112

16.5

79

9 401

54

14.8

81

‘overdiagnosis’ refers to clinical outcome events not adjusted for disease that would remain clinically covert until death from other causes. If there is considerable overdiagnosis, an apparently favorable screening result in regard to stage or 5-year survival would not lead to a significant lung cancer mortality reduction in the screened arm. With current information it is not possible to establish a reliable estimate of the magnitude of overdiagnosis, but emerging clinical and biologic information suggests that these small screen-detected lung cancers may behave like symptom-detected lung cancers.21,22 Furthermore, the term ‘overdiagnosis’ is used loosely and may be construed to include the situation where a clinically aggressive lung cancer is detected by CT screening. However, in certain situations overdiagnosis also refers to the patient who expires first of a co-morbid condition related to tobacco yeast. In the decades since the last major NCI-sponsored lung cancer screening trials, the influence of competing risks has diminished related to both improved coronary artery disease outcomes and the increasing number of former smokers perhaps mitigating the influence of overdiagnosis.6,23–25 Finally, overdiagnosis could also be construed as cases where lethal iatrogenic complications occur in the course of clinical management of screen-detected lesions.26 Overtreatment refers to the use of an intervention that may entail greater morbidity than benefit of screening that may be accrued to an individual choosing to undergo lung cancer screening. The best clinical management for small CT-detected primary cancers is emerging to be different from the standard management recommended for a chest X-raydetected lung cancer.27,28 For example, an anatomic lobectomy with mediastinal dissection is the appropriate operation to manage a chest X-ray-detected lung cancer, but is it the best way to remove a 7 mm peripheral primary lung cancer? Since even with subcentimeter screen-detected primary cancers, the frequency of regional nodal involvement remains around 10%, the

optimal size range for finding lung cancers before lymphatic dissemination must be even smaller. Nevertheless, the evidence for more favorable outcomes in managing smaller primary lung cancers is growing.29–36 From the experience in Tokyo, Rochester (MN), New York City, and Milan, it is evident that centers of excellence can deliver high-quality lung cancer screening care and measures reducing the number of invasive diagnostic procedures improve cost efficiencies.8,33,37–40 Professional groups such as the Society for Thoracic Surgery have developed national registries as a tool for improving quality outcomes in thoracic surgery (http://www.sts.org/doc/8406), and these measures may allow favorable management outcomes to become more generalized.4,41 Currently, the best approach to reducing overtreatment, and with it the morbidity and mortality of screening case management, is an area of uncertainty, but clear research opportunities exist and preliminary studies in this regard are being undertaken.42–45 An important finding at both Mayo Clinic and Cornell is that smoking cessation counseling in the setting of lung cancer screening is associated with favorable quit rates.46,47 Tobacco control has been the dominant public health response for improving lung cancer outcomes.48 Linking smoking cessation with early detection research efforts may improve the cost economy of lung cancer screening. In light of the reports suggesting spiral CT can detect small, early lung cancer, the NCI rapidly initiated the National Lung Cancer Screening Trial (NLST) to evaluate whether CT screening leads to a significant improvement in lung cancer-related mortality. This urgency was heightened by the concern that widespread ad hoc CT screening, despite being a non-reimbursed service, could preempt the opportunity for conducting a formal randomized trial. Based on favorable initial data, many people believe that lung cancer screening will be a sensitive test for early disease. While this may be true for many individuals, from a public health policy perspective it is also necessary to place emphasis on the

Current status of lung cancer screening 55

specificity of a screening test. The specificity of the screening test will affect the resultant costs to society, in terms of morbidity and dollars, in regard to overdiagnosis, overtreatment, false positives, and adverse events associated with appropriate treatment. Conventional wisdom is that these factors can only be assessed in a prospective, randomized trial with a control group and a lung cancer mortality endpoint. The NLST, which has already completed full accrual, uses multi-detector-row scanners (at least four rows) for the 25 000 volunteers on the CT arm of that trial. The control group of 25 000 receives annual chest X-ray screening. The NLST subjects will receive annual screening for three years, and follow-up will continue for a few years until a mortality endpoint is reached. The Dutch national randomized CT screening trial will use 16-detector scanners and computer-assisted-detection (CAD) tools for their entire study population and compare outcomes with a standard care control arm. Other European trials including studies in France and Italy are coming online. Investigators from the American and European trials will have periodic meetings to standardize elements of data acquisition so that comparison of results from the various trials may be more productive. While breast cancer screening trials were conducted over several decades with relative stability of the imaging detection tool,49 the dynamic pace of innovation with spiral CT and its consequences have imposed an unprecedented challenge to the randomized trial design concept.50,51 Thoughtful analysis of the relative utility of different trial designs, large databases, and other resources in permitting adaptive public health progress is a profound strategic challenge, but one that merits more serious attention.19,41

TECHNICAL INNOVATIONS WITH CT IMAGING Over the last decade, there have been substantial improvements in the speed and quality of CT imaging. Ten years ago, a typical single-detector CT scanner acquiring one centimeter thick views (slices) along the entire axial length of the thorax took several minutes and consequently the respiratory motion of chest structures seriously compromised image resolution. Since then there have been several generations of multi-detector CT scanners; the latest 64-detector-row scanners will image the entire thorax using 0.625 mm slice thicknesses in several seconds. This thinner slice thickness may allow for markedly better image resolution, but the

amount of data generated in this process is daunting. Currently, the average size of incident primary cancers detected at one center is under 1.0 cm.27,52,53 The gap between the technical capabilities of the hardware in acquiring vast amounts of imaging data and the availability of validated software to harness this improved imaging capability highlights the importance of research into CAD for early cancers. A potential benefit of higher-resolution imaging is that the evaluation may be more sensitive in finding smaller primary cancers. This size reduction may further decrease the frequency of metastatic disease as well as interval-detected cancer.27– 32 A particular problem in this regard is the reliable detection of curable small cell lung cancer cases. CAD has not had a major clinical impact on breast cancer imaging,54 but this is a two-dimensional data situation. With the anatomically more precise, three-dimensional spiral CT, this situation could be different for lung cancer. The additional information provided by the third dimension greatly improves the precision of measurement and of volume comparisons across time.55–57 If CT screening is validated to be effective, many more lung CT scans will be performed. Even with screening high-risk cohorts, the frequency of cancer in a high-risk population will typically be about 1% or less, so software to allow efficient work flow is essential to leveraging the productivity of thoracic radiologists. However, to reliably establish clinically relevant features such as the irregular boundary of small pulmonary lesions abutting normal adjacent structures, the amount of imaging information required by a CAD system may exceed the amount of imaging information that it is reasonable to expect a radiologist to review. This disconnection will be most evident when CAD is being applied to evaluate very small lesions, where human vision has limited capabilities and determining the ‘ground truth’ will be problematic. Therefore, developing and validating CAD applications for cancer screening are great challenges, but standardized image evaluation tools may prove essential in moving population-based lung cancer screening into routine care settings.54,58–60 For this reason, the NCI developed the Lung Image Database Consortium (LIDC) to accelerate the maturation of image-processing tools for CAD. The key aspect of this cooperative group is to create a large, well-characterized database of images and clinical outcomes data for CAD algorithm research and validation. This resource could expedite such projects as the utility of volumetrically determined growth rates for identifying potential cancerous pulmonary nodules53,61 or studies on the natural history of newly reported

56 Textbook of Lung Cancer

ground-glass opacities (or non-solid nodules).39,42,62 Rapid progress with CT-based imaging is expected to continue. To extract clinically significant information from such a detail-rich image, computer-assisted tools will be crucial. The further pragmatic issues encountered in the breast cancer screening efforts in regard to radiologists’ workload, reimbursement, and professional liability may also be ameliorated if validated computer-aided diagnosis methods are developed.63,64 A major concern about widespread CT screening relates to its cost, especially in light of one study which projected enormous costs from models assembled using assumptions based on early screening reports.15 More extensive use of non-invasive imaging techniques in the work-up of screen-detected lesions may explain why the cost features of some screening management approaches are less expensive.65 Only 13% of the screened cases require further follow-up, with most of those cases evaluated by serial CT imaging for nodule growth rate.52,53,61 Further potential for cost savings and morbidity reductions can be achieved by carefully

defining the risk features of the screened cohort,66 by reducing the screening intensity in following up screen-negative populations,67 as well as from further innovation with the imaging technology.

RECOMMENDATIONS FROM PROFESSIONAL SOCIETIES The American Cancer Society (ACS) updated its statement on testing for early lung cancer and recommended against testing for early lung cancer in the asymptomatic population of at-risk individuals.68 However, this revised statement recommends that individuals at high risk for lung cancer, due to significant exposure to tobacco smoke or occupational exposure, should discuss with their physician the potential benefits and harm to inform their testing decision. ACS further recommends that such testing be done only in experienced centers linked to multidisciplinary specialty groups for diagnosis and follow-up.69

Table 6.2 Points to consider for clinicians in discussing lung cancer screening and its implications with individuals considering spiral CT screening

• • • •

• • •

• • • •

The risk and benefits of lung cancer screening should be discussed, including potential morbidity, mortality, and associated medical costs No data are available from the two randomized trials evaluating for improvement in lung cancer-related mortality and results are expected in several years Results from observational studies of CT screening among high-risk patients (i.e. those with a history of heavy smoking) indicate a high rate of diagnosis of lung cancer in stage I (a relatively curable stage) The risk:benefit issues around lung cancer screening may be different for current smokers compared to former smokers. • For current smokers, smoking cessation remains the single most important measure to improve one’s overall but especially cardiovascular health prospects • For former smokers, the elevated risk of developing lung cancers persists for the rest of their lives CT screening reveals many non-calcified nodules, only a fraction of which will be found to be lung cancer The approach to diagnostic evaluation of suspicious nodules should be refined to maximize information yield from non-invasive procedures while minimizing iatrogenic risk Referral to a facility that is experienced and committed to providing high-quality integrated screening care is essential. At such a facility there would be experienced and credentialed clinicians from multidisciplinary fields (including thoracic surgeon, pathologist, pulmonologist) The surgeon selected to perform the lung cancer operation should not only be specifically trained to provide such care but should also perform lung cancer operations frequently Facilities providing lung cancer screening care should provide objective information about the quality of their outcomes There is a persistent increased risk of subsequent lung cancers after curative resection of lung cancer, so ongoing surveillance is essential Participation in research to optimize CT screening management should be strongly encouraged

Current status of lung cancer screening 57

The conclusions from the USPSTF analysis, based on a review of the literature published as of January 2003, (http://www.ahrq.gov/clinic/uspstf/uspslung.htm) are as follows: The USPSTF recommends neither for nor against using chest x-ray, computed tomography (CT scan), or sputum cytological examination to look for lung cancer in people who have no symptoms to suggest the disease. If screening is being considered, doctors and patients should discuss the pros and cons of screening before going ahead with x-ray, CT scan, or sputum cytologic examination to screen for lung cancer. Patients should be aware that there are no studies showing that screening helps people live longer. They should also know that false-positive test results are common and can lead to unnecessary worry, testing, and surgery.12 This statement represents a change from their previous recommendation against screening and this reflects the accumulation of more persuasive though not yet definitive data regarding the utility of lung cancer screening. As a reflection of the extraordinary pace of this field, a number of relevant reports have been published since the completion of the USPSTF literature review on new cohorts,18,38,39 efficiency of the diagnostic work-up,27,53,70 outcomes,72,73 and cost-effectiveness.45,65 In this dynamic setting, clinicians have a major challenge in staying abreast to provide current information to their patients. Issues to consider in discussion with a patient who may be considering lung cancer screening are complex. In light of recent reports about health literacy there is a major communications challenge in responsibly educating about lung cancer screening (see http://www.iom.edu/report.asp?id=19723 and http:// www.ahrq.gov/clinic/epcsums/litsum.htm). Since the clinical management for lung cancer screening has a higher probability of morbid and mortal complications than cancer screening for other organs, a mortality reduction benefit found by the NLST may not result in improved national outcomes with lung cancer if screening care delivery systems for early lung cancer are not in place.41 The choice is between organized screenings, where screening services are provided in centers committed to excellence in early cancer management, or ad hoc screening, where the specifics of screening care are left to be refined by market forces. We recently tried to organize a series of issues that should help physicians organize their dialog with subjects considering lung cancer screening.72

RECENT DEVELOPMENTS The New England Journal of Medicine recently published a landmark experience in using spiral CT in over 31 000 individuals at risk for lung cancers from 38 institutions across three continents.73 Over the last 15 years, the group at Cornell, together with their collaborators, has systematically explored the best approach to finding and operating on early lung cancer. In a series of peerreviewed publications they have defined innovative uses of spiral CT, image processing techniques, and internet-based clinical trial co-ordination, driving progress in the detection and management of early lung cancer. There is controversy about the benefit of CTbased screening for lung cancer, but there should be no argument about the core strategy of attempting to improve our ability to routinely find early, localized lung cancer. In community-based populations, finding early lung cancer is a daunting process since disease prevalence is relatively low. Finding economic approaches to detect and confirm the occurrence of lung cancer in this setting is a critical public health challenge. The Cornell group has described a successful approach to this and has integrated minimally invasive diagnostic and surgical techniques as feasible for early lung cancer management. In addition, they have worked with a number of the most respected thoracic pathologists in the world (mostly from IASLC) to review these cases and, in their recent publication, reported that the cases found by CT screening fulfill standard criteria for fully fledged aggressive lung cancers.74 This supports recent tumor biology information suggesting that these screen-detected tumors behave like routinely detected lung cancers.22 Of the more than 400 cancers recently reported in the Cornell study, 85% of the detected cases were stage I. The 10-year survival analysis, after three years of median follow-up, shows that over 90% of the people undergoing operations were projected to be alive and lung cancer free. All eight individuals who for personal reasons declined surgery died of lung cancer. A key enabler of this large study consortium was the use of a web-based early lung cancer management system developed by the Cornell group which allowed research to go on in the setting of clinical care. The current I-ELCAP results convincingly demonstrate that systematic efforts to find early lung cancer can be associated with very favorable outcomes and their organizational process accelerates early lung cancer research. A challenging debate is proceeding about the sufficiency

58 Textbook of Lung Cancer

of the I-ELCAP data to change national health-care policy on lung cancer screening. This is a profoundly important scientific, medical, and political process. However, the IASLC could play a pivotal role in generating the research data to inform the process. There are many steps in moving to responsible management of early lung cancer and we need better information about all of them. How do we identify the optimal cohort, how do we do the diagnostic work-up, how do we do the most appropriate removal of the primary cancer, how frequently do we do follow-up CT scans to find synchronous primaries, etc. These and many more issues need to be addressed with research using stateof-the-art imaging tools. Since the progress in improving imaging tools is moving so fast, it is a major challenge for our research processes. This is a part of the discussion about early detection research that merits much more serious and urgent research attention. The contentious discussion surrounding screening trial design has distracted us from a profound emerging opportunity to much more successfully manage lung cancer.

CONCLUSION CT screening for lung cancer detection has considerable promise. Yet many individuals seeking lung cancer screening services, such as the lower-risk subject outlined in the introductory vignette, may have a greater chance of iatrogenic harm that screening benefit. While definitive trials are in progress, the opportunity should not be lost to conduct further essential research to generalize a potential mortality reduction benefit evident in a lung cancer screening trial to routine care settings. REFERENCES 1. Jemal A, Tiwari RC, Murray T et al. Cancer statistics, 2004. CA Cancer J Clin 2004; 54: 8–29. 2. Patel JD, Bach PB, Kris MG. Lung cancer in US women: a contemporary epidemic. JAMA 2004; 291: 1763–8. 3. Tong L, Spitz MR, Fueger JJ, Amos CA. Lung carcinoma in former smokers. Cancer 1996; 78: 1004–10. 4. Warner EE, Mulshine JL. System engineering lung cancer screening with spiral CT: how could it work? Oncology 2004; 18: 564–75. 5. Enstrom JE, Heath CW Jr. Smoking cessation and mortality trends among 118 000 Californians, 1960–1997. Epidemiology 1999; 10: 500–12. 6. CDC. Annual smoking-attributable mortality, years of potential life lost and economic cost – United States 1995–1999. MMWR 2002; 51: 300–3.

7. Leaf C. Why we’re losing the war on cancer and how to win it. Fortune 2004; 149: 76–96. 8. Henschke CI, McCauley DI, Yankelevitz DF et al. Early Lung Cancer Action Project: overall design and findings from baseline screening. Lancet 1999; 354: 99–105. 9. Henschke CI, Yankelevitz DF, McCauley DI et al. Guidelines for the use of spiral computed tomography in screening for lung cancer. Eur Respir J Suppl 2003; 39: 45s–51s. 10. Kaneko M, Kusumoto M, Kobayashi T et al. Computed tomography screening for lung carcinoma in Japan. Cancer 2000; 89: 2485–8. 11. Mulshine J. Screening for lung cancer: in pursuit of pre-metastatic disease. Nature Rev Cancer 2003; 3: 65–73. 12. Humphrey LL, Teutsch S, Johnson M. Lung cancer screening with sputum cytological examination, chest radiography and computer tomography: an update for the U.S. Preventive Task Force. Ann Intern Med 2004; 140: 740–53. 13. Strauss G, Dominioni L. Varese meeting report. Lung Cancer 1999; 23: 171–2. 14. Fontana RS, Sanderson DR, Woolner LB et al. Screening for lung cancer. A critique of the Mayo Lung Project. Cancer 1991; 67: 1155–64. 15. Mahadevia PJ, Fleisher LA, Frick KD et al. Lung cancer screening with helical computed tomography in older adult smokers: a decision and cost-effectiveness analysis. JAMA 2003; 289: 313–22. 16. Swensen SJ, Jett JR, Midthun DE, Hartman TE. Computer tomographic screening for lung cancer: home run or foul ball? Mayo Clin Proc 2003; 78: 1187–8. 17. Brenner DJ. Radiation risks potentially associated with lowdose CT screening of adult smokers for lung cancer. Radiology 2004; 231: 440–5. 18. Kakinuma R. Low-dose helical CT screening for lung cancer: the Japanese experience and perspective. Proc IASLC Workshop 2003: 18. 19. Henschke CI, Yankelevitz D. Lung cancer screening with spiral CT: how can it work: reviewed. Oncology 2004; 18: 584–7. 20. Wisnivesky JP, Mushlin AI, Sicherman N et al. The cost-effectiveness of low-dose CT screening for lung cancer: preliminary results of baseline screening. Chest 2003; 124: 614–21. 21. Bianchi F, Hu J, Pelosi G et al. Screening spiral CT-detected lung cancers have a malignant phenotype by cDNA microarray analysis. Clin Cancer Res 2004; 10: 6023–8. 22. Mulshine JL, Weinstein JN. Is the gene expression pattern different in lung cancer detected by screening spiral CT rather due to symptoms? Clin Cancer Res 2004; 10: 5973–4. 23. CDC. Cigarette smoking among adults – United States 2000. MMWR 2002; 51: 642–5. 24. Lenfant C. Shattuck lecture – clinical research to clinical practice – lost in translation? N Engl J Med 2003; 349: 868–74. 25. Ambrogi V, Pompeo E, Elia S et al. The impact of cardiovascular comorbidity on the outcome of surgery for stage I and II non-small-cell lung cancer. Eur J Cardio-Thorac Surg 2003; 23: 811–17. 26. Warner EE, Mulshine JL. Surgical considerations with lung cancer screening. J Surg Oncol 2003; 84: 1–6. 27. Henschke CI, Yankelevitz DF, Naidich DP et al. CT Screening for lung cancer: suspiciousness of nodules according to size on baseline scans. Radiology 2004; 231: 164–8.

Current status of lung cancer screening 59 28. Ginsberg RJ, Rubinstein LV. Randomized trial of lobectomy versus limited resection for T1 N0 non-small cell lung cancer. Lung Cancer Study Group. Ann Thorac Surg 1995; 60: 615–22; discussion 622–3. 29. Mountain CF. Revisions in the International System for Staging Lung Cancer. Chest 1997; 111: 1710–17. 30. Mountain CF. Staging classification of lung cancer. A critical evaluation. Clin Chest Med 2002; 23: 103–21. 31. Martini N, Bains MS, Burt ME et al. Incidence of local recurrence and second primary tumors in resected stage I lung cancer. J Thorac Cardiovasc Surg 1995; 109: 120–9. 32. Martini N, Rusch VW, Bains MS et al. Factors influencing tenyear survival in resected stages I to IIIa non-small cell lung cancer. J Thorac Cardiovasc Surg 1999; 117: 32–6; discussion 37–8. 33. Henschke CI, Naidich DP, Yankelevitz DF et al. Early lung cancer action project: initial findings on repeat screenings. Cancer 2001; 92: 153–9. 34. Gajra A, Newman N, Gamble GP et al. Impact of tumor size on survival in stage IA non-small cell lung cancer: a case for subdividing stage IA disease. Lung Cancer 2003; 42: 51–7. 35. Fang D, Zhang D, Huang G et al. Results of surgical resection of patients with primary lung cancer: a retrospective analysis of 1,905 cases. Ann Thorac Surg 2001; 72: 1155–9. 36. Konaka C, Ikeda N, Hiyoshi T et al. Peripheral non-small cell lung cancers 2.0 cm or less in diameter: proposed criteria for limited pulmonary resection based upon clinicopathological presentation. Lung Cancer 1998; 21: 185–91. 37. Swensen SJ, Jett JR, Hartman TE et al. Lung cancer screening with CT: Mayo Clinic experience. Radiology 2003; 226: 756–1. 38. Pastorino U, Bellomi M, Landoni C et al. Early lung-cancer detection with spiral CT and positron emission tomography in heavy smokers: 2-year results. Lancet 2003; 362: 593–7. 39. Kakinuma R, Ohmatsu H, Kaneko M et al. Progression of focal pure ground-glass opacity detected by low-dose helical computed tomography screening for lung cancer. J Comput Assist Tomogr 2004; 28: 17–23. 40. Geraghty PR, Kee ST, McFarlane G et al. CT-guided transthoracic needle aspiration biopsy of pulmonary nodules: needle size and pneumothorax rate. Radiology 2003; 229: 475–81. 41. Smith RA. Lung cancer screening with spiral CT: how can it work, reviewed. Oncology 2004; 18: 578–3. 42. Asamura H, Suzuki K, Watanabe S et al. A clinicopathological study of resected subcentimeter lung cancers: a favorable prognosis for ground glass opacity lesions. Ann Thorac Surg 2003; 76: 1016–22. 43. Okada M, Yoshikawa K, Hatta T, Tsubota N. Is segmentectomy with lymph node assessment an alternative to lobectomy for non-small cell lung cancer of 2 cm or smaller? Ann Thorac Surg 2001; 71: 956–60; discussion 961. 44. Sugarbaker DJ, Strauss GM. Extent of surgery and survival in early lung carcinoma: implications for overdiagnosis in stage IA nonsmall cell lung carcinoma. Cancer 2000; 89: 2432–7. 45. Tsushima Y, Endo K. Analysis models to assess cost effectiveness of the four strategies for the work-up of solitary pulmonary nodules. Med Sci Monit 2004; 10: MT65–72. 46. Ostroff JS, Buckshee N, Mancuso CA et al. Smoking cessation following CT screening for early detection of lung cancer. Prev Med 2001; 33: 613–21.

47. Cox LS, Clark MM, Jett JR et al. Change in smoking status after spiral chest computed tomography scan screening. Cancer 2003; 98: 2495–501. 48. Peto R, Chen ZM, Boreham J. Tobacco – the growing epidemic. Nat Med 1999; 5: 15–17. 49. Shapiro S. Screening: assessment of current studies. Cancer 1994; 74: 231–8. 50. Sackett DL, Wennberg JE. Choosing the best research design for each question. BMJ 1997; 315: 1636. 51. Concato J, Shah N, Horwitz RI. Randomized, controlled trials, observational studies, and the hierarchy of research designs. N Engl J Med 2000; 342: 1887–92. 52. Kostis WJ, Reeves AP, Yankelevitz DF, Henschke CI. Threedimensional segmentation and growth-rate estimation of small pulmonary nodules in helical CT images. IEEE Trans Med Imaging 2003; 22: 1259–74. 53. Kostis WJ, Yankelevitz DF, Reeves AP et al. Small pulmonary nodules: reproducibility of three-dimensional volumetric measurement and estimation of time to follow-up CT. Radiology 2004; 231: 446–52. 54. Gur D, Sumkin JH, Rockette HE et al. Changes in breast cancer detection and mammography recall rates after the introduction of a computer-aided detection system. J Natl Cancer Inst 2004; 96: 185–90. 55. Ambrose J, Hounsfield G. Computerized transverse axial tomography. Br J Radiol 1973; 46: 148–9. 56. Wormanns D, Fiebich M, Saidi M et al. Automatic detection of pulmonary nodules at spiral CT: clinical application of a computer-aided diagnosis system. Eur Radiol 2002; 12: 1052–7. 57. Reeves AP, Kostis WJ. Computer-aided diagnosis for lung cancer. Radiol Clin North Am 2000; 38: 497–509. 58. Beam CA, Layde PM, Sullivan DC. Variability in the interpretation of screening mammograms by US radiologists. Findings from a national sample. Arch Intern Med 1996; 156: 209–13. 59. Elmore JG, Carney PA. Computer-aided detection of breast cancer: has promise outstripped performance? J Natl Cancer Inst 2004; 96: 162–3. 60. Bassett LW, Monsees BS, Smith RA et al. Survey of radiology residents: breast imaging training and attitudes. Radiology 2003; 227: 862–9. 61. Yankelevitz DF, Reeves AP, Kostis WJ et al. Small pulmonary nodules: volumetrically determined growth rates based on CT evaluation. Radiology 2000; 217: 251–6. 62. Henschke CI, Yankelevitz DF, Mirtcheva R et al. CT screening for lung cancer: frequency and significance of part-solid and nonsolid nodules. Am J Roentgenol 2002; 178: 1053–7. 63. Enzmann DR, Anglada PM, Haviley C, Venta LA. Providing professional mammography services: financial analysis. Radiology 2001; 219: 467–73. 64. Kopans DB. Mammography screening is saving thousands of lives, but will it survive medical malpractice? Radiology 2004; 230: 20–4. 65. Wisnivesky JP, Mushlin AI, Sicherman N, Henschke C. The cost-effectiveness of low-dose CT screening for lung cancer: preliminary results of baseline screening. Chest 2003; 124: 614–21. 66. van Klaveren RJ, de Koning HJ, Mulshine J, Hirsch FR. Lung cancer screening by spiral CT. What is the optimal target population for screening trials? Lung Cancer 2002; 38: 243–52.

60 Textbook of Lung Cancer 67. Nawa T, Nakagawa T, Kusano S et al. Lung Cancer Screening Using Low-Dose Spiral CT: results of baseline and 1-year follow-up studies. Chest 2002; 122: 15–20. 68. Smith RA, Cokkinides V, Eyre HJ. American Cancer Society Guidelines for the Early Detection of Cancer, 2003. CA Cancer J Clin 2003; 53: 27–43. 69. Smith RA, Cokkinides V, Eyre HJ. American Cancer Society Guidelines for the Early Detection of Cancer, 2004. CA Cancer J Clin 2004; 54: 41–52. 70. Libby DM, Smith JP, Altorki NK et al. Managing the small pulmonary nodule discovered by CT. Chest 2004; 125: 1522–9.

71. Sobue T, Moriyama N, Kaneko M et al. Screening for lung cancer with low-dose helical computed tomography: anti-lung cancer association project. J Clin Oncol 2002; 20: 911–20. 72. Mulshine JL, Sullivan DC. Clinical practice. Lung cancer screening. N Engl J Med 2005; 352: 2714–20. 73. International–Early Lung Cancer Action Program Investigators. Survival of patients with Stage I lung cancer detected on CT screening. N Engl J Med 2006; 355: 1763–71. 74. Flieder DB, Vazque M, Carter D. Pathological findings of lung tumors diagnosed on baseline CT screening. Am J Surg Pathol 2006; 30: 606–13.

7

Histopathology of lung tumors Elisabeth Brambilla, Sylvie Lantuejoul Contents Introduction • Squamous cell carcinoma • Adenocarcinoma • Small cell carcinoma • Large cell carcinoma • Adenosquamous carcinoma • Sarcomatoid carcinoma • Typical and atypical carcinoid • Conclusions

INTRODUCTION With 169 500 new cases per year in the United States and 182 000 new cases per year in Europe, lung cancer is the most common worldwide diagnosed cancer and the major cause of mortality,1 with157 400 cancer deaths2 in the USA and 190 000 cancer deaths in the European Union in 2001. Although cancer incidence began to decline in men in the USA from 1980,3 its rate is increasing in women,2 as a consequence of the increasing proportion of women who smoke. The international standard for histologic classification of lung tumors is that proposed by the World Health Organization (WHO) and the International Association for the Study of Lung Cancer (IASLC; Table 7.1).4 The four major histologic types of lung cancer are squamous cell carcinoma, adenocarcinoma, the incidence of which is increasing at the expense of squamous cell carcinoma, small cell carcinoma (SCLC), and large cell carcinoma. These major types have been subclassified into subtypes, the clinical significance of which might be extremely important, such as the bronchioloalveolar carcinoma (BAC) as a variant of adenocarcinoma.4 Although lung cancer can be divided into many subtypes, the most important distinction is between SCLC and non-small cell lung carcinoma (NSCLC). Clinical importance has been given to this distinction because of the major clinical differences in presentation, metastatic spread, and response to therapy of SCLC. However, this is an extremely simplistic means of distinction between these subtypes which is not recommended because it may override the clinical significance of specific subtypes like BAC. Histologic heterogeneity is an important feature of the pathology of lung cancer, which consists of a mixture of histologic types that represent a derivation of lung cancer from a pluripotent stem cell.5–10 This histologic heterogeneity is apparent on light microscopic examination in at least 30% of

lung cancers, and is even more frequently seen by electron microscopy.

SQUAMOUS CELL CARCINOMA A malignant epithelial tumor showing keratinization and/or intercellular bridges that arises from bronchial epithelium.11 Squamous cell carcinoma (SCC) accounts for approximately 30% of all lung cancers in the United States12 and 45% in Europe. Twenty years ago it was the most frequent histologic type of lung cancer in Europe, and it has progressively decreased, while adenocarcinoma has increased in incidence. Over 90% of SCC occurs in cigarette smokers. Two-thirds of SCCs present as central tumors, whereas one-third present as peripheral tumors, although the primary bronchial site may be easily detected at histology.13,14 The morphologic features that characterize squamous differentiation include intercellular bridging and keratinization (or individual cell keratinization or squamous pearl formation). These differentiated features are readily apparent in well-differentiated tumors, and are difficult to detect in poorly differentiated ones.15 However, this spectrum of differentiation has not been demonstrated to correlate with prognosis in lung SCC. Segmental bronchi more often than lobar and mainstem bronchi are the primary site of SCC.16 Variants described in the WHO classification include papillary, clear cell, small cell,17 and basaloid subtypes.4 This last variant has a dismal prognosis as compared to poorly differentiated SCC.18,19 In a recent evaluation of a large series of cases where basaloid carcinoma appeared to have a shorter survival than other types of NSCLC (p = 0.005) the basaloid variant of SCC did not differ from pure basaloid cases with regard to survival.20 Papillary SCC often shows a pattern of exophytic endobronchial growth.21,22

62 Textbook of Lung Cancer Table 7.1 WHO histologic classification of tumors of the lung

Table 7.1 Continued

Malignant epithelial tumors Squamous cell carcinoma Papillary Clear cell Small cell Basaloid

8070/3 8052/3 8084/3 8073/3 8083/3

Small cell carcinoma Combined small cell carcinoma

8041/3 8045/3

Adenocarcinoma Adenocarcinoma, mixed subtype Acinar adenocarcinoma Papillary adenocarcinoma Bronchioloalveolar carcinoma Non-mucinous Mucinous Mixed non-mucinous and mucinous or indeterminate Solid adenocarcinoma with mucin production Fetal adenocarcinoma Mucinous (‘colloid’) carcinoma Mucinous cystadenocarcinoma Signet ring adenocarcinoma Clear cell adenocarcinoma

8140/3 8255/3 8550/3 8260/3 8250/3 8252/3 8253/3 8254/3

Large cell carcinoma Large cell neuroendocrine carcinoma Combined large cell neuroendocrine carcinoma Basaloid carcinoma Lymphoepithelioma-like carcinoma Clear cell carcinoma Large cell carcinoma with rhabdoid phenotype

8012/3 8013/3 8013/3

Adenosquamous carcinoma

8560/3

Sarcomatoid carcinoma Pleomorphic carcinoma Spindle cell carcinoma Giant cell carcinoma Carcinosarcoma Pulmonary blastoma

8033/3 8022/3 8032/3 8031/3 8980/3 8972/3

Carcinoid tumor Typical carcinoid Atypical carcinoid

8240/3 8240/3 8249/3

8230/3 8333/3 8480/3 8470/3 8490/3 8310/3

8123/3 8082/3 8310/3 8014/3

(Continued)

Salivary gland tumors Mucoepidermoid carcinoma Adenoid cystic carcinoma Epithelial-myoepithelial carcinoma Preinvasive lesions Squamous carcinoma in situ Atypical adenomatous hyperplasia Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia Mesenchymal tumors Epithelioid hemangioendothelioma Angiosarcoma Pleuropulmonary blastoma Chondroma Congenial peribronchial myofibroblastic tumor Diffuse pulmonary lymphangiomatosis Inflammatory myofibroblastic tumor Lymphangioleiomyomatosis Synovial sarcoma Monophasic Biphasic Pulmonary artery sarcoma Pulmonary vein sarcoma Benign epithelial tumors Papillomas Squamous cell papilloma Exophytic Inverted Glandular papilloma Mixed squamous cell and glandular papilloma Adenomas Alveolar adenoma Papillary adenoma Adenomas of the salivary gland type Ta Mucous gland adenoma Pleomorphic adenoma Others Mucinous cystadenoma Lymphoproliferative tumors Marginal zone B-cell lymphoma of the MALT type Diffuse large B-cell lymphoma

8430/3 8200/3 8562/3 8070/2

9133/1 9120/3 8973/3 9220/0 8827/1

8825/1 9174/1 9040/3 9041/3 9043/3 8800/3 8800/3

8052/0 8052/0 8053/0 8260/0 8560/0

8251/0 8260/0 8140/0 8940/0 8470/0 9699/3 9680/3 (Continued)

Histopathology of lung tumors 63

Table 7.1 Continued

Lymphomatoid granulomatosis Langerhans cell histiocytosis Miscellaneous tumors Harmatoma Sclerosing hemangioma Clear cell tumor Germ cell tumors Teratoma, mature Immature Other germ cell tumors Intrapulmonary thymoma Melanoma Metastatic tumors

9766/1 9751/1

8832/0 8005/0 9080/0 9080/3 8580/1 8720/3

From WHO Classification of Tumors, 2004. Behavior is coded /0 for benign tumors, /3 for malignant tumors, and /1 for borderline or uncertain behavior.

ADENOCARCINOMA A malignant epithelial tumor with glandular differentiation or mucin production, showing acinar, papillary, bronchioloalveolar, or solid with mucin growth patterns, or a mixture of these patterns. Adenocarcinoma can be classified into: • • • •

• • • • •

adenocarcinoma mixed subtype; acinar adenocarcinoma; papillary adenocarcinoma; bronchioloalveolar carcinoma; – non-mucinous – mucinous – mixed non-mucinous and mucinous – solid adenocarcinoma with mucin production. Variants are: fetal adenocarcinoma; mucinous (‘colloid’) carcinoma; mucinous cystadenocarcinoma; signet ring adenocarcinoma; clear cell adenocarcinoma.

Adenocarcinomas account for about 30% of lung cancers in Europe and the USA.12 Most primary pulmonary adenocarcinomas, in contrast with metastases, are highly heterogeneous and consist of a mixture of histologic subtypes. Most adenocarcinomas are histologically heterogeneous, consisting of two or more of the histologic subtypes and whilst a majority of the lung adenocarcinomas diagnosed are classified today into

the mixed subtype. For this reason the adenocarcinoma mixed subtype was moved to the top of the list of adenocarcinoma subtypes in the 2004 WHO classification, although it was not recognized in the 1981 WHO classification.23 The acinar and papillary subtypes are recognized by their architectural pattern of tumor cell growth and invasion. A substantially different definition has been given to bronchioloalveolar carcinoma (BAC subtype), which should be restricted to tumors that grow in a purely lepidic fashion without invasion of stroma, blood vessels, or pleura. The solid type is a poorly differentiated carcinoma presenting intracytoplasmic mucins that should be of at least five mucin droplets in two different high-power fields. Mucin stains recommended are PAS (periodic acid–Schiff) with diastase digestion and Kreyberg staining with alcian blue. Several additional unusual variants have also been recognized, such as well-differentiated fetal adenocarcinoma,24 mucinous (‘colloid’) adenocarcinoma,25 mucinous cystadenocarcinoma,26–28 signet ring carcinoma,29 and clear cell adenocarcinoma.4 Two unusual gross patterns of adenocarcinoma include the endobronchial polypoid adenocarcinoma30 and pseudomesotheliomatous adenocarcinoma.31–33 Bronchioloalveolar carcinoma is uncommon, and probably restricted to fewer than 5% of all lung malignancies.12 In the new 1999 WHO/IASLC classification, BAC is defined as a tumor showing lepidic growth along pre-existing alveolar septa with intact elastic and basal lamina frames, without invasive growth. It should be noticed that some increased fibrotic collagen deposit of alveolar walls is accepted, as long as no myofibroblastic proliferation is visible. The lack of invasive growth is added as an essential criterion4 based on clinico-pathologic data indicating that in patients with less than a 2 cm tumor, BAC may be curable by economic surgical resection.34 As a result of the narrow criteria for BAC, the term ‘adenocarcinoma, mixed subtype’ is used for tumors that have BAC and an invasive component. In such cases the invasive patterns present (acinar, papillary, or solid) should be mentioned. It is common to observe central scars in pulmonary adenocarcinoma that contain invasive components and a focal BAC-like pattern at the periphery of the tumor. As a consequence of this revised definition of BAC, the literature dealing with these tumors need complete re-evaluation. Indeed, previous to the last classification, BAC included tumors with obvious invasive growth.23,35,36 More than 50% of tumors previously classified as BACs presented focal central desmoplastic scarring tissue or

64 Textbook of Lung Cancer

intra-alveolar complex papillary growth while the lepidic growth started around the edge of the scar.37 For tumors showing malignant tumor cell nests in a desmoplastic stromal reaction, the diagnosis is adenocarcinoma mixed subtype and the various subtypes present should be mentioned (such as acinar, papillary, or BAC). These are no longer considered as pure BAC.13,37 In addition, filling of alveolar lumens by papillary or micropapillary structures is considered to be papillary adenocarcinoma, but not bronchioloalveolar carcinoma. BAC has two major cytologic subtypes, non-mucinous and mucinous,4 and are rarely mixed, consisting of an association of mucinous and non-mucinous cells.4 The majority of BACs are mucin-producing, followed by the non-mucinous type, while about 12% are a mixture of both.37,38 Non-mucinous BACs consist of Clara cells and type II pneumocytes; the latter cell type is a common stem cell for distal bronchioles and alveoli identified in fetal lung and is nowadays considered as the lung adenocarcinoma stem cell.39 The non-mucinous BACs are more likely to be solitary38 than the mucinous type. These tumors are composed of cuboidal cells proliferating along alveolar septa and showing a hobnail appearance. Specific nuclear inclusions are patent in half of the nonmucinous tumor cells that are stained with diastasedigested PAS and immunohistochemically for surfactant apoprotein. On electron microscopy, these inclusions form a network of 40-nm diameter microtubules.40,41 The mucin-producing BACs tend to be more multicentric and characteristically have mucin production.38 They may cause lobar consolidation resembling pneumonia on gross examination. Histologically, these tumors consist of tall columnar cells with abundant apical cytoplasmic mucin and small, basally oriented, regular bland nuclei lining thin alveolar septa. Alveolar and bronchiolar spaces are filled with abundant mucin. According to the 1999 WHO/IASLC classification, a final diagnosis of BAC can only be achieved on examination of a surgical resection specimen. Small biopsies obtained by bronchoscopy or fine needle sampling may show a lepidic growth pattern suggesting the possibility of BAC, but are not sufficient to exclude the presence of an invasive growth. Pathoradiologic correlations There are several growth presentations for the most common adenocarcinoma mixed subtype with BAC: • •

a solitary nodule; multiple nodules;

• •

lobar consolidation; diffuse (pseudopneumonic) consolidation pattern.

The typical radiologic appearance of BAC (pure BAC or BAC component) is the ground glass pattern by CT and an ill-defined, aerated, spongy density on gross examination. In contrast, a grossly circumscribed nodule at growth examination and a pure solid appearance on CT is typical of purely invasive adenocarcinoma (acinar, papillary, solid). In between, a mixture of these growths and CT appearances is seen in mixed subtype adenocarcinoma with both invasive (often centrally located) components and BAC component (often peripheral). When BAC and other adenocarcinomas present with multiple nodules they can be unilateral or bilateral. Unilateral nodules are classified as T4 by the TNM classification and multiple nodules in another lobe are classified as M1. Lobar consolidation and diffuse pseudopneumonic condensation patterns are difficult to distinguish grossly or radiologically from infective pneumonia. All cases of adenocarcinoma presenting with a diffuse or pseudopneumonic consolidation pattern have been shown to correspond to mixed subtype adenocarcinoma with BAC component. They are more frequently of the mucinous cell type, with varying amounts of acinar, papillary, and solid components. Prognostic correlations with solitary small peripheral lung nodules Several important clinico-pathologic studies have shown the clinical significance of BAC.34,42,43 Noguchi et al34 reported that, in a large series of 236 peripheral lung adenocarcinomas less than 2 cm in size, the patients achieved 100% 5-year survival. These were pure BACs, in contrast to patients with ‘invasive BAC’ who experienced higher mortality and a 5-year survival of 75%, while the purely invasive form had a 5-year survival of 52%. Suzuki et al42 demonstrated that the size of the fibrotic scar was correlated with survival in a series of 100 peripheral adenocarcinomas less that 3 cm in size: a 5-year survival of 100% was recorded for patients with a scar size of 5 mm or less, in contrast to 70% for patients with scars 5 to 15 mm in size and 40% for patients with a central scar greater than 15 mm. In this study, the size of central fibrosis was an independent prognostic factor on multivariate analysis (p = 0.01), as significant as vascular invasion (p = 0.024) and lymph node metastasis (p = 0.024). Yokose et al43 studied multiple pathologic factors for prognostic assessment in 200 patients: 100% 5-year

Histopathology of lung tumors 65

survival was associated with at least one of the following features: • • •

a pattern of lepidic growth of more than 75%; a central scar measuring 5 mm or less; lack of destruction of the elastic fiber framework by tumor cells.43

The most significant determinants of shorter survival in the multivariate analysis were vascular invasion (p < 0.001) and more than 25% papillary or invasive growth (p = 0.043). Size and grade/pattern of stromal invasion44,45 also influence survival. This has practical consequences: all small (≤3 cm) tumors with a predominant BAC component should be entirely sampled serially, and included so that potential foci of invasion are detected. BAC is not a unique feature for lung adenocarcinoma since about 15% of digestive mucinous carcinoma metastases might mimic the histologic appearance of BAC. Thyroid transcription factor-1 (TTF-1) immunostaining restricted to primary lung adenocarcinoma is of great help in this distinction.

SMALL CELL CARCINOMA A malignant epithelial tumor consisting of small cells with scant cytoplasm, ill-defined cell borders, finely granular nuclear chromatin, and absent or inconspicuous nucleoli. The cells are round, oval, and spindle-shaped. SCLC accounts for 25% of all lung cancers in the USA as well as in Europe.12 Two-thirds of SCLCs are proximal and present as a perihilar tumor. They occur in a bronchial location, infiltrating the bronchial submucosa and subsequently leading to bronchial obstruction by circumferential compression. SCLCs are not commonly observed on a surgical specimen since extensive lymph node metastasis is common and the tumor is not surgically curable. Macroscopically the tumor is soft, friable, white-tan, and extensively necrotic. Extensive lymph node metastasis is very frequent and less than 5% of cases present as a solitary coin lesion.46,47 The 1999 WHO/IASLC classification presents only two types of SCLC: SCLC (with pure SCLC histology) and combined SCLC (combined with any non-small cell type) (see Table 7.1).4 The two subtypes oat cell carcinoma and intermediate cell type, that were proposed in the 1981 WHO classification, as well as the category of mixed small cell, large cell, proposed in 1988 by the IASLC, were discarded from the new classification

because of difficulties in reproducibility of these subtypes and lack of confirmation that these patients have a different prognosis.48,49 SCLC has a distinctive histologic appearance. The tumor cells have a small size, not exceeding that of three lymphocytes. They have a round or fusiform shape, scant cytoplasm with a nuclear to cytoplasmic ratio of 9 to 10, a finely granular nuclear chromatin (‘salt and pepper’ appearance), and absent or inconspicuous nucleoli.4 Owing to the scarcity of cytoplasm, nuclear molding and smearing of nuclear chromatin is frequent, caused by crush artifacts. There is usually extensive necrosis and a mitotic rate exceeding 20 and reaching 100 mitoses per 2 mm2 area. Most often, the growth pattern consists of diffuse sheets, although endocrine differentiations with rosettes, palisading, ribbons, and organoid nesting might be seen.50 Basophilic encrustation of vessel walls is known as the Azzopardi effect in necrotic areas.50 Depending on the biopsy specimens, the tumor cell size of SCLC might appear larger, which is often the case in well-fixed open biopsies. Fine needle aspiration (FNA) biopsy and core biopsy may provide excellent material for assessment of the diagnosis of SCLC, essentially because cytologic features of SCLC have a high diagnostic value and the architecture is not critical for the diagnosis. The small cell proliferation, with nuclear moulding, the very high nuclear to cytoplasmic ratio, and the ‘salt and pepper’ quality of chromatin are extremely useful for this diagnosis on FNA. The diagnostic markers (NE markers, TTF-1, absence of CK34βE12 expression) are of primary help in the diagnosis of SCLC. There is an excellent yield of these markers on FNA and/or biopsy. Combined small cell lung cancer The frequency of combined SCLC depends on the extent of histologic sampling, and the extent of the associated component. Combined SCLC represents about 10%49 of SCLC if small biopsies are considered. However, in a recent study on surgically treated SCLC, using a conservative estimate of 10% of tumors showing associated NSCLC for subclassifying a tumor as a combined variant of SCLC, 28% of the cases of SCLC showed a combination with NSCLC, more commonly with large cell lung carcinoma followed by adenocarcinoma and squamous cell carcinoma.48,49,51–53 SCLC can also be associated, although rarely, with spindle cell carcinoma,54,55 giant cell carcinoma,54 and carcinosarcoma.56 Immunohistochemistry might help to differentiate associated components, such as cytokeratin antibody

66 Textbook of Lung Cancer

cocktails, which tend to stain NSCLC components, a good example of which is cytokeratin 1, 5, 10, 14 recognized by 34βE12.57 However, evidence is lacking that pure and combined SCLC behaves differently with regard to prognosis and response to therapy.51 Following chemotherapy, a mixture of large cells, squamous cells, adenocarcinoma or giant cells with SCLC may be seen in 15 to 45% of the cases.52,58–60 Differential diagnosis Because SCLC has distinctive clinical properties with an aggressive clinical course, frequent widespread metastasis of presentation, common paraneoplastic syndrome, and responsiveness to chemotherapy, histologic classification of lung cancer often is simplified into SCLC versus NSCLC. A constellation of criteria is applied for the distinction between SCLC and large cell neuroendocrine carcinoma (LCNEC) including cell size, nucleoli, nuclear-to-cytoplasmic ratio, nuclear chromatin pattern, nuclear molding, cell shape (fusiform versus polygonal), and Azzopardi phenomenon (Table 7.2).4,23,61,62 Disagreement among expert lung cancer pathologists over this distinction occurs in up to 10% of cases,10,63 owing to the fact that sometimes LCNEC may adopt the nuclear features of SCLC. With the new description of LCNEC, the main differential resides in the distinction

of SCLC from LCNEC (Table 7.2). Crush artifact is common in small biopsy specimens owing to scarcity of stromal protection; this can also be seen in carcinoid tumors, lymphocytic infiltrates, or poorly differentiated NSCLC. In these cases, cytology specimens might be helpful because the morphology may be more diagnostic than on a small biopsy specimen. Immunohistochemistry for neuroendocrine differentiation, keratins, and common leukocyte antigen (lymphoid marker) can be useful in marking SCLC versus lymphoid cells, respectively.64 TTF-1 has been shown to be of great help in distinguishing between SCLCs, which are 85% positive for TTF-1 nuclear staining, and other proliferating small cells such as the small cell variant of squamous cell carcinoma and basaloid carcinoma, both of which are always TTF-1 negative.57,65 The most useful and specific neuroendocrine markers for distinction of SCLC in formalin-fixed, paraffin-embedded tissue sections are chromogranin A, synaptophysin, and neural cell adhesion molecule, especially the 123C3 clone and CD56.61,66–70 Keratin (AE1/AE3) and epithelial membrane antigen (EMA) as well as TTF-1 stain virtually all SCLCs in open lung biopsy and transbronchial biopsy specimens.57,61,65,66 In contrast, a specific set of cytokeratins never expressed in neuroendocrine proliferations (CK 1, 5, 10, 14) called 34βE12 is always absent in pure SCLC. In the cases where common cytokeratins

Table 7.2 Light microscopic features for distinguishing small cell carcinoma and large cell neuroendocrine carcinomaa Histologic feature

Small cell carcinoma

Large cell neuroendocrine carcinoma

Cell size

Larger

Nuclear/cytoplasmic ratio Nuclear chromatin

Smaller (less than diameter of 3 lymphocytes) Higher Finely granular, uniform

Nucleoli

Absent or faint

Nuclear molding Fusiform shape Polygonal shape with ample pink cytoplasm Nuclear smear Basophilic staining of vessels and stroma

Characteristic Common Uncharacteristic

Lower Coarsely granular or vesicular, less uniform Often (not always) present, may be prominent or faint Less prominent Uncommon Characteristic

Frequent Occasional

Uncommon Rare

a

From Travis WD, Linnoila RI, Tsokos MG, et al.61 Neuroendocrine tumors of the lung with proposed criteria for large-cell neuroendocrine carcinoma. An ultrastructural, immunohistochemical, and flow cytometric study of 35 cases. Am J Surg Pathol 15: 529–533, 1991; with permission.

Histopathology of lung tumors 67

Table 7.3 Histochemical differential diagnosis between small cell lung carcinoma (SCLC), basaloid carcinoma, and large cell neuroendocrine carcinoma (LCNEC)

SCLC Basaloid carcinoma LCNEC

NE markers

TTF-1

Cytokeratins 1, 5, 10, 14

+ −

+ −

− +

+

+/−

−

are negative in a suspected SCLC, the pathologist should exclude other possibilities such as chronic inflammation, lymphoma (CD45 positive), primitive neuroectodermal tumor, or small cell round sarcoma. One difficulty resides in the fact that about 25% of SCLCs express the antigen CD99/MIC-2, as do primitive neuroectodermal tumors and small round cell sarcoma. It is important to recognize that this distinction is based primarily on light microscopy (Table 7.2).4 Since no single monoclonal antibody can reliably distinguish SCLC from NSCLC,70,71 a set of reliable markers should be considered (Table 7.3).

LARGE CELL CARCINOMA Large cell carcinoma is a tumor that shows no differentiation pattern to allow classification into squamous cell carcinoma, adenocarcinoma, or small cell carcinoma. These poorly differentiated tumors most often arise in the lung periphery, although they may be located centrally. They frequently appear at gross examination as large, necrotic tumors. Histologically, these consist of sheets or nests of large polygonal cells with vesicular nuclei and prominent nucleoli.23 Although they are undifferentiated by light microscopy, features of squamous cell or adenocarcinoma might be found on electron microscopy examination.6,7,72 There are several variants of large cell carcinoma, some of which have high clinical significance, recognized in the new WHO/IASLC histologic classification of lung cancer (Table 7.1).4 These include LCNEC,4,61,73 basaloid carcinoma,18,19,74 lymphoepithelial-like carcinoma,75–77 clear cell carcinoma,78 and large cell carcinoma with rhabdoid phenotype.79 Lymphoepithelial-like carcinoma is described as an EBV (Epstein–Barr virus) dependent epithelial proliferation more commonly seen in the upper respiratory tract.

Because lung cancers are classified according to the best differentiated component, areas of large cell carcinoma are frequently observed in poorly differentiated adenocarcinoma or squamous cell carcinoma, and due to the common heterogeneity of these cancers it is difficult to specifically and appropriately classify many lung cancers in which only small pieces of tissue are available. In such cases, the best diagnosis might be ‘non-small cell carcinoma’ and specification of the most obvious component.5,80,81 Large cell neuroendocrine carcinoma LCNEC is a variant of large cell carcinoma. It is a highgrade non-small cell neuroendocrine carcinoma that differs from atypical carcinoid and small cell carcinoma. Histologic criteria include: (1) neuroendocrine morphology (organoid, palisading, trabecular, or rosette-like growth patterns; (2) non-small cell cytologic features (large size, polygonal shape, low nuclear to cytoplasmic (N/C) ratio, coarse or vesicular nuclear chromatin, and obvious nucleoli); (3) high mitotic rate (≥11 per 2 mm2) with a mean of 60 mitoses per 2 mm2; (4) frequent necrosis; and (5) at least one positive neuroendocrine immunohistochemical specific marker or neuroendocrine granules by electron microscopy.4,61 It is difficult to diagnose LCNEC based on small biopsy specimens because of frequent lack of neuroendocrine morphology without a substantial sampling of the tumors. Some criteria have been proposed based on cytology.82 The term combined LCNEC is used for tumors associated with other histologic types of NSCLC, such as adenocarcinoma or squamous cell carcinoma (Table 7.1).4 Any combination of LCNEC with SCLC is diagnosed as SCLC combined.4 A variety of criteria must be used to separate SCLC from LCNEC (Table 7.2). Differential diagnosis In 10% of the cases of NSCLC lacking neuroendocrine morphology, immunohistochemical neuroendocrine markers or neuroendocrine granules by electron microscopy can be demonstrated. Such tumors are called nonsmall cell carcinomas (adenocarcinoma, squamous cell carcinoma, or large cell carcinoma) with neuroendocrine differentiation (NSCLC-NED).4,61 Although Iyoda et al83 found that the tumor size of large cell carcinoma with

68 Textbook of Lung Cancer

neuroendocrine differentiation was significantly larger than that for LCNEC, the survival was not different in this series from patients with LCNEC. At the present time, the clinical significance of the diagnosis of NSCLCNED is not known. Whether these tumors are responsive to SCLC chemotherapy regimens84–86 or whether expression of neuroendocrine markers may be an unfavorable prognostic factor87–94 remains to be determined.

show no staining in small cell, large cell and LNEC whereas it stains quite all basaloid carcinoma. TTF-1 is never present in basaloid carcinoma, but is present in the majority of SCLC and LCNEC (Table 7.3).57,95 p63 is expressed in most cells of all basaloid carcinomas.

Basaloid carcinoma Basaloid carcinoma is the most prominent variant of large cell carcinoma after LCNEC.4,18,74 Basaloid carcinoma represents 3 to 4% of NSCLCs in Europe, almost always occurs in males, and most of these tumors develop in proximal bronchi where they frequently have an endobronchial component. Two-thirds of these tumors arise from long areas on the bronchial mucosa and show prolonged and laterally extended in situ carcinoma. About half of the tumors present with a pure basaloid pattern that belongs to a variant of large cell carcinoma. The remaining cases have minor (less than 50%) components of squamous cell carcinoma or, more rarely, adenocarcinoma and are thus classified as squamous cell carcinoma (basaloid variant) or adenocarcinoma, respectively. These tumors consist of a lobular, trabecular, or palisading gross pattern of relatively small monomorphic cuboidal to fusiform cells with moderately hyperchromatic nuclei, finely granular chromatin, absent or only focally conspicuous nucleoli, scant cytoplasm but a nuclear to cytoplasmic ratio lower than that of SCLC, and a high mitotic rate from 20 to 100 mitoses per 2 mm2. Neither intercellular bridges nor individual cell keratinization are present which allows them to be distinguished from poorly differentiated squamous cell carcinoma. Patients with basaloid carcinoma have a significantly shorter survival than those with poorly differentiated squamous cell carcinoma which deserves this differential diagnosis.18,19,74

Adenosquamous carcinoma accounts for 0.6 to 2.3% of all lung cancers96–100 and is defined as a lung carcinoma having at least 10% of squamous cell or adenocarcinoma components.4 Adenosquamous carcinoma should not be confused with mucoepidermoid carcinoma, a malignant epithelial tumor characterized by the presence of squamoid cells, mucin-secreting cells, and cells having intermediate type, identical to the same tumors encountered in the salivary glands. Mucoepidermoid carcinoma of high-grade malignancy is differentiated from adenocarcinoma by a variety of features including a mixture of mucin-containing cells and squamoid cells, transition areas from classic low-grade mucoepidermoid carcinoma, and lack of keratinization.

Differential diagnosis Since comedo type necrosis is common, palisading is a characteristic feature of basaloid carcinoma, and rosettes can be identified in about one-third of cases, the main differential diagnosis resides in separation from LCNEC. Immunohistochemical stains for neuroendocrine markers are negative in basaloid carcinoma and positive in LCNEC. No secretory granules have been seen by electron microscopy in basaloid carcinoma. Two antibodies are helpful to make the distinction on small biopsies between basaloid carcinoma, SCLC, and LCNEC. The specific cytokeratins 1, 5, 10, 14 recognized by 34βE12

ADENOSQUAMOUS CARCINOMA

SARCOMATOID CARCINOMA This group of lung carcinomas is poorly differentiated and expresses a spectrum of pleomorphic, sarcomatoid, and sarcomatous elements. They express the features and the biological behavior of epithelial cells that adopt an epithelial to mesenchymal transition in certain conditions of culture in vitro. Pleomorphic carcinomas tend to be large peripheral tumors invading bronchial lumens, forming endobronchial growth. They often invade the chest wall and are associated with a poor prognosis.54 Because of the characteristic histologic heterogeneity of this tumor, adequate sampling is required and should consist of at least one section per centimeter of the tumor diameter. To enter in this category a pleomorphic carcinoma should have at least a 10% component of spindle or giant cells associated with, but distinctly identifiable from, other histologic types such as adenocarcinoma or squamous cell carcinoma.4 A few giant cells disseminated in an otherwise recognizable squamous cell adenocarcinoma or SCLC have no value for classification in the category of sarcomatoid carcinoma. Rarely carcinomas present with a pure giant cell or spindle cell pattern and deserve the terms giant cell or spindle cell carcinoma. Giant cell carcinoma consists of

Histopathology of lung tumors 69

huge, bizarre, pleomorphic and multinucleated tumor cells that engulf numerous inflammatory cells, particularly polymorphonuclear leukocytes, in their cytoplasm.101– 103 They are discohesive and separated by significant infiltration of inflammatory cells. This tumor is defined as a carcinoma by light microscopy, but immunohistochemical and epithelial markers such as keratins are also quite helpful in confirming their epithelial nature.4 Carcinosarcoma Carcinosarcoma is a tumor composed of a mixture of carcinoma and sarcoma. A heterologous component should be demonstrated such as cartilage, bone, or skeletal muscle – heterologous elements which do not display cytokeratin staining.4 Experience proves that these cases are extremely rare while observations of pseudochondromatous or pseudo-osseous patterns in sarcomatoid carcinoma are frequent: in these cases the pseudosarcomatous components also express keratins. Pulmonary blastoma Pulmonary blastomas are defined as biphasic tumors consisting of an association of a glandular component that resembles well-differentiated fetal adenocarcinoma and a primitive sarcomatous or mesenchymal component.4 Well-differentiated fetal adenocarcinoma is no longer regarded as the epithelial pattern of monophasic pulmonary blastoma but, rather, as a variant of adenocarcinoma.4

TYPICAL AND ATYPICAL CARCINOID Carcinoid tumors accounts for 1 to 2% of all invasive lung malignancies.12 The majority of patients are asymptomatic at presentation.104 Symptoms include hemoptysis, postobstructive pneumonitis, dyspnea, paraneoplastic syndromes including carcinoid, Cushing’s syndrome,104–106 and acromegaly.107 There is no gender predilection.104,108 There is no association with smoking since 40% of patients with carcinoid are non-smokers, which is the proportion within the normal population. The mean age is 55 years, with a range up to 82 years.104 This is the most common lung tumor in childhood.109 The treatment of choice of pulmonary carcinoids is surgical resection.104,110 Patients with typical carcinoid (TC) have an excellent prognosis and rarely die from their tumors.104,111 However, metastases do not disqualify the diagnosis of typical carcinoid. Five to ten percent of TCs have regional lymph node involvement that does

not affect their clinical outcome.13 Compared with TC, atypical carcinoid (AC) presents with a larger tumor size, higher rate of metastases, and a significantly reduced survival. Most series where the diagnosis was based on actual accepted criteria reported a mortality of 27 to 47%.104,112–114 Carcinoid tumors are most often centrally located with a polypoid endobronchial obstructive component. When peripheral carcinoids occur they are more often of the spindle cell type. Both TC and AC are characterized histologically by an endocrinoid, organoid growth pattern and uniform cytologic features, consisting of moderate eosinophilic, finely granular cytoplasm, a nucleus with a finely granular chromatin (Table 7.4), and inconspicuous nucleoli that can be discretely more prominent in AC. A variety of histologic patterns may occur in AC and TC, including trabecular, palisading, rosette-like, papillary, sclerosing papillary, glandular, paragangliomatous, spindle cell, and follicular patterns.61 More rarely, the tumor cells of pulmonary carcinoid tumors may have oncocytic, acinic cell-like, signet ring, mucin-producing, or melanocytic features.61 The most distinguishing feature between typical carcinoid and atypical carcinoid is the rate of mitosis and the presence or absence of necrosis. Typical carcinoids show less than 2 mitoses per 2 mm2 area of viable tumor (per 10 high power field) and no necrosis. The presence of between 2 and 10 mitoses per 2 mm2 or necrosis73 defines the diagnosis of atypical carcinoids. The presence of features such as cell pleomorphism, vascular invasion, and increased cellularity are of no help in separating TC from AC and in allowing stratification of patients for prediction of survival.73 TC may well show focal cytologic pleomorphism, as do paragangliomas in the head and neck area.61,112 The necrosis in AC usually consists of small foci centrally located within organoid nests of tumor cells. Immunohistochemistry Nearly 80% of TC and AC stain for pancytokeratins and, as other pulmonary neuroendocrine tumors, they always express cytokeratins 8, 18, and 19.115 From a more practical standpoint, expression of cytokeratins 1, 5, 10, and 14 has never been observed along the whole spectrum of neuroendocrine tumors of the lung.116 Neuroendocrine markers are present in all carcinoids. Chromogranin A is present in neurosecretory granules and synaptophysin is contained in synaptic vesicles.68 They all express CD 56/NCAM, which belong to the immunoglobulin superfamily of transmembrane

70 Textbook of Lung Cancer Table 7.4 Typical and atypical carcinoid: distinguishing features Histologic or clinical feature

Typical carcinoid

Atypical carcinoid

Histologic patterns: organoid, trabecular, palisading, and spindle cell Mitoses

Characteristic

Characteristic

Absent or <2 per 2 mm2 area of viable tumor (10 high power fields on some microscopes) Absent

2–10 per 2 mm2 or area of viable tumor (10 high power fields on some microscopes) Characteristic, usually focal or punctate Often present

Necrosis Nuclear pleomorphism, hyperchromatism Regional lymph node metastases at presentation Distant metastases at presentation Survival at 5 years

Usually absent, not sufficient by itself for diagnosis of AC 5–15%

Disease-free survival at 10 years

40–48%

Rare

20%

90–95%

58%

90–95%

35%

adhesion molecules, and to date, as for other neuroendocrine tumors of the lung, NCAM remains the most useful immunohistochemical marker, even on crushed biopsies or small specimens, in the differential diagnosis with papillary adenocarcinoma and sclerosing hemangioma. In contrast, as widely reported, NSE immunostaining is of little help in the diagnosis of neuroendocrine tumors in general because of its lack of specificity.69,117 TTF-1 expression was demonstrated to be negative in the spectrum of neuroendocrine hyperplasia, tumorlets, and typical and carcinoid tumors.118 However, other authors have reported some TTF-1 expression in nearly one-third of TC and AC,119,120 predominantly in a peripheral location.121 This discrepancy could be related to differences in immunohistochemical techniques or in assessing the threshold of positivity. TTF-1 expression has not been demonstrated in cDNA expression profiling, whereas it is in high-grade NE tumors of poor prognosis.122 Concerning the proliferation antigen Ki 67 in carcinoids, staining is observed in less than 10%, and an index higher than 4%, more frequently observed in AC, seems to be related to a shorter survival.123,124 Differential diagnosis Carcinoids differ from tumorlets by the size of the latter, which do not exceed 5 mm in diameter. Sclerosing

hemangiomas may resemble carcinoids, especially with a papillary or pseudoglandular pattern. The demonstration of neuroendocrine markers and absence of TTF-1 expression distinguish carcinoids from sclerosing hemangiomas.124 Carcinoids may be confused with paragangliomas, but this lesion remains very rare in the lung, and the lack of cytokeratin expression in the latter has a discriminative feature. Glomus tumors and other smooth muscle tumors may mimic carcinoids, from which they are distinguished by the presence of smooth muscle actin and the absence of neuroendocrine markers. Adenocarcinoma enters the differential diagnosis because a gland-like pattern occurs in carcinoids. Mucin production is not a definitive distinguishing feature since carcinoids may disclose mucin formation. TTF-1 expression and the absence of neuroendocrine markers in adenocarcinoma are of great help. The solid type adenoid cystic carcinoma may be mistaken for carcinoid, but is negative for neuroendocrine markers.

CONCLUSIONS Histologic subclassification of lung tumors is essentially based on light microscopy in order to achieve the widest application through the world and assume comparability and consistency of data. However, techniques including immunohistochemistry, electron microscopy,

Histopathology of lung tumors 71

tissue culture, and molecular biology might provide valuable information on carcinogenesis, histogenesis, and differentiation. It is well recognized that immunohistochemistry and electron microscopy may detect differentiation, specifically regarding the histologic heterogeneity of lung cancer, that cannot be seen by routine light microscopy. However, these techniques are occasionally required for precise classification. An example of this is LCNEC and malignant mesothelioma, which require appropriate immunohistochemical and/or electron microscopic findings to confirm the diagnosis.

15.

16.

17.

18.

19.

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Histopathology of lung tumors 73 70. Brambilla E, Veale D, Moro D et al. Neuro-endocrine phenotype in lung cancers:comparison of immunochemistry with biochemical determination of enolase isoenzymes. Am J Clin Pathol 1992; 98: 88–97. 71. Tome Y, Hirohashi S, Noguchi M et al. Preservation of cluster 1 small cell lung cancer antigen in zinc-formalin fixative and its application to immunohistological diagnosis. Histopathology 1990; 16: 469–74. 72. Kodama T, Shimosato Y, Koide T et al. Large cell carcinoma of the lung – ultrastructural and immunohistochemical studies. Jpn J Clin Oncol 1985; 15: 431–41. 73. Travis WD, Rush W, Flieder DB et al. Survival analysis of 200 pulmonary neuroendocrine tumors with clarification of criteria for atypical carcinoid and its separation from typical carcinoid. Am J Surg Pathol 1998; 22: 934–44. 74. Brambilla E. Basaloid of the lung. In: Corrin B, ed. Pathology of Lung Tumors. New York, Edinburgh, London, Melbourne, San Francisco and Tokyo: Churchill Livingstone, 1997. 75. Butler AE, Colby TV, Weiss L et al. Lymphoepithelioma-like carcinoma of the lung. Am J Surg Pathol 1989; 13: 632–9. 76. Chan JK, Hui PK, Tsang WY et al. Primary lymphoepithelioma-like carcinoma of the lung. A clinicopathologic study of 11 cases. Cancer 1995; 76: 413–22. 77. Pittaluga S, Wong MP, Chung LP et al. Clonal Epstein–Barr virus in lymphoepithelioma-like carcinoma of the lung. Am J Surg Pathol 1993; 17: 678–82. 78. Katzenstein AL, Prioleau PG, Askin FB. The histologic spectrum and significance of clear-cell change in lung carcinoma. Cancer 1980; 45: 943–7. 79. Cavazza A, Colby TV, Tsokos M et al. Lung tumors with a rhabdoid phenotype. Am J Clin Pathol 1996; 105: 182–8. 80. Chuang MT, Marchevsky A, Teirstein AS et al. Diagnosis of lung cancer by fibreoptic bronchoscopy: problems in the histological classification of non-small cell carcinomas. Thorax 1984; 39: 175–8. 81. Haratake J, Horie A, Tokudome S et al. Inter- and intra-pathologist variability in histologic diagnoses of lung cancer. Acta Pathol Jpn 1987; 37: 1053–60. 82. Wiatrowska BA, Krol J, Zakowski MF. Large-cell neuroendocrine carcinoma of the lung: proposed criteria for cytologic diagnosis. Diagn Cytopathol 2001; 24: 58–64. 83. Iyoda A, Hiroshima K, Toyozaki T et al. Clinical characterization of pulmonary large cell neuroendocrine carcinoma and large cell carcinoma with neuroendocrine morphology. Cancer 2001; 91: 1992–2000. 84. Gazdar AF, Kadoyama C, Venzon D et al. Association between histological type and neuroendocrine differentiation on drug sensitivity of lung cancer cell lines. Monogr Natl Cancer Inst 1992; 191–6. 85. Graziano SL, Mazid R, Newman N et al. The use of neuroendocrine immunoperoxidase markers to predict chemotherapy response in patients with non-small-cell lung cancer. J Clin Oncol 1989; 7: 1398–406. 86. Linnoila RI, Jensen SM et al. Neuroendocrine (NE) differentiation in non-small cell lung cancer (NSCLC) correlates with favorable response to chemotherapy. Proce Am Soc Clin Oncol 1989; 8: 248. 87. Berendsen HH, de Leij L, Poppema S et al. Clinical characterization of non-small-cell lung cancer tumors showing

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74 Textbook of Lung Cancer 105. Pass HI, Doppman JL, Nieman L et al. Management of the ectopic ACTH syndrome due to thoracic carcinoids. Ann Thorac Surg 1990; 50: 52–7. 106. Ricci C, Patrassi N, Massa R et al. Carcinoid syndrome in bronchial adenoma. Am J Surg 1973; 126: 671–7. 107. Scheithauer BW, Carpenter PC, Bloch B et al. Ectopic secretion of a growth hormone-releasing factor. Report of a case of acromegaly with bronchial carcinoid tumor. Am J Med 1984; 76: 605–16. 108. el-Naggar AK, Ballance W, Karim FW et al. Typical and atypical bronchopulmonary carcinoids. A clinicopathologic and flow cytometric study. Am J Clin Pathol 1991; 95: 828–34. 109. Lack EE, Harris GB, Eraklis AJ et al. Primary bronchial tumors in childhood. A clinicopathologic study of six cases. Cancer 1983; 51: 492–7. 110. Stamatis G, Freitag L, Greschuchna D. Limited and radical resection for tracheal and bronchopulmonary carcinoid tumour. Report on 227 cases. Eur J Cardiothorac Surg 1990; 4: 527–32. 111. Warren WH, Gould VE. Long-term follow-up of classical bronchial carcinoid tumors. Clinicopathologic observations. Scand J Thorac Cardiovasc Surg 1990; 24: 125–30. 112. Arrigoni MG, Woolner LB, Bernatz PE. Atypical carcinoid tumors of the lung. J Thorac Cardiovasc Surg 1972; 64: 413–21. 113. Bonato M, Cerati M, Pagani A et al. Differential diagnostic patterns of lung neuroendocrine tumours. A clinico-pathological and immunohistochemical study of 122 cases. Virchows Arch A Pathol Anat Histopathol 1992; 420: 201–11. 114. Paladugu RR, Benfield JR, Pak HY et al. Bronchopulmonary Kulchitzky cell carcinomas. A new classification scheme for typical and atypical carcinoids. Cancer 1985; 55: 1303–11. 115. Brambilla E, Brambilla C. Hétérogénéité des cancers bronchiques. Problèmes d’histogénèse. Rev Mal Resp 1986; 5: 235–45. 116. Sturm N, Rossi G, Lantuejoul S et al. 34β E12 expression along the whole spectrum of neuroendocrine proliferations of

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8

Clinical diagnosis and basic evaluation John J Mullon, Eric J Olson Contents Introduction • History • Physical examination • Imaging • Diagnostic techniques • Overview of basic evaluation • Future developments

INTRODUCTION

HISTORY

Lung cancer is the most lethal of all malignant diseases worldwide and remains the leading cause of cancerrelated death in the United States.1 Lung cancer is responsible for the overall increase in cancer mortality noted over the second half of the 20th century in the USA, which since 1999 has exceeded heart disease as the leading cause of death in those less than 85 years of age.1 Although the overall death rates due to lung cancer have decreased in the USA and western Europe since 1991, largely due to reductions in tobacco smoking,2,3 global lung cancer incidence and mortality rates are expected to continue to rise as a result of the ongoing tobacco use in countries with developing or transitional economies.4 Three- to five-year diseasefree rates for resected stage I lung cancer as high as 60 to 90% are reported, but less than 20% of all lung cancers are stage I at the time of diagnosis and five-year survival rates for all stages of lung cancer remain approximately 15%.1 It is imperative that clinicians be familiar with the evaluation of lung cancer given its tremendous worldwide public health impact and the prognostic importance of early cancer detection. Lung cancer outcome depends on the cell type and stage of disease at presentation based on the TNM classification. Accordingly, the essential aspects of lung cancer evaluation are the histologic distinction of small cell (SCLC) and non-small cell (NSCLC) types and accurate determination of the extent of disease so that appropriate treatment can be initiated. The evaluation of lung cancer begins with a careful history and physical exam, followed by testing to obtain a tissue diagnosis and stage the extent of disease. This chapter will review aspects of clinical presentation, imaging, and diagnostic testing for bronchogenic carcinoma. Details regarding staging are discussed elsewhere in this text.

Lung cancers are clinically silent for the majority of time as they theoretically grow from a single malignant cell to a potentially detectable lesion. The vast majority of patients diagnosed with lung cancer are symptomatic at the time of diagnosis. In only about 10% of cases is lung cancer discovered incidentally in an asymptomatic patient, for instance as a solitary pulmonary nodule on a routine chest radiograph. Smoking history,5 concurrent chronic obstructive pulmonary disease (COPD),6 and previous exposures to certain environmental and occupational carcinogens,7 including environmental tobacco smoke,8 predict a higher risk for bronchogenic carcinoma. Ethnic and racial differences also contribute to the smoking-related risk of lung cancer, with African Americans and native Hawaiians within the USA at higher risk.9 Local tumor growth, regional extension, metastases, paraneoplastic phenomenon, or a combination of mechanisms may cause tumor-associated symptoms (Table 8.1). There are no characteristics of clinical presentation which absolutely distinguish NSCLC and SCLC. Local effects The most common initial symptom of lung cancer is cough, which occurs in 45–75% of patients,10 and may be productive in up to 27%.11 Bronchorrhea, the expectoration of large-volume, thin, mucoid secretions, may be seen with advanced bronchioloalveolar carcinoma (BAC), but is rare. Due to the location of vagal afferent cough receptors, which principally line the airway mucosa, cancer types with a predilection for central airway involvement (notably SCLC or NSCLC in the form of squamous cell carcinoma) may cause cough earlier in their course, whereas peripherally located tumors such as adenocarcinoma or large cell carcinoma may only cause cough as a late symptom. In addition to bronchial mucosa tumor invasion, causes of cough may include

76 Textbook of Lung Cancer Table 8.1 Aspects of lung cancer presentation

Asymptomatic Symptomatic Effects of local tumor growth Cough Bronchorrhea Fever, chills, purulent sputum production (postobstructive pneumonitis) Dyspnea Hemoptysis Chest pain Wheeze Stridor Effects of regional tumor extension Hemidiaphragm paralysis Hoarseness Dysphagia Bronchoesophageal fistula Pericardial effusion/tamponade/ tachyarrhythmias Lymphangitic carcinomatosis Pulmonary nodules Tumor microembolism Pleural effusion Superior vena cava syndrome Pancoast syndrome Metastatic effects Adrenal Liver Central nervous system Bone Paraneoplastic effects See Table 8.2

postobstructive pneumonitis/atelectasis, tumor cavitation, or pleural effusion. Although cough is a nonspecific symptom frequently present in patients with co-existent smoking-related airways disease, a change in the character of a chronic cough, such as new hemoptysis or co-existent fever and chills, should raise suspicion of an additional process such as lung cancer. Lung cancer is overall an unusual cause of chronic cough, occurring in less than 2% of patients,12 and is even less likely in the setting of a normal chest radiograph.13 One-third to one-half of patients initially report dyspnea that may arise from large airway obstruction, postobstructive pneumonitis/atelectasis, pleural effusion, lymphangitic metastases, pericardial effusion, or concurrent illnesses such as COPD. Dyspnea in a lung

cancer patient with a normal chest X-ray may be due to pulmonary thromboembolism or, less commonly, tumor microembolism. Lung cancer presents with hemoptysis in many patients as a result of tumor necrosis, mucosal ulceration, tumor erosion into pulmonary vasculature, postobstructive pneumonia, and pulmonary thromboembolism. Retrospective studies reveal that bronchogenic carcinoma accounts for 19–29% of cases of hemoptysis.14,15 In patients with a normal chest radiograph and hemoptysis, only 2–9% are subsequently found to have lung cancer.16 Hemoptysis is commonly blood-streaked sputum, although large central tumors may lead to massive hemoptysis that can result in death by asphyxiation. Tumor involvement of the parietal pleura, chest wall, and mediastinum leads to chest pain as an initial complaint in 25–50% of patients.17 Other causes of pain include rib cage metastases, pulmonary embolism, and postobstructive pneumonitis. Pneumothorax is a rare cause of chest pain and dyspnea in lung cancer patients. Regional extension effects Direct mediastinal extension by lung cancer or metastases to mediastinal lymph nodes can lead to a variety of presentations due to the diversity of adjacent structures. Phrenic nerve involvement by tumor may cause ipsilateral diaphragmatic paralysis demonstrated on chest X-ray by hemidiaphragm elevation often in the setting of a centrally located mass. If lung cancer is not initially identified as the etiology of diaphragm paralysis, it is unlikely to become the explanation over time.18 Hoarseness, a finding at presentation in 5–18% of lung cancer patients,17 is usually attributable to unilateral left vocal paralysis resulting from damage to the left recurrent laryngeal nerve anywhere along its intrathoracic course. Extrinsic esophageal compression by tumor or metastatic lymph nodes may cause dysphagia. Postprandial coughing raises the possibility of bronchoesophageal fistula. Pericardial involvement, which may be present in 20% of patients,17 occurs by hematogenous, lymphatic, or direct extension routes, and may cause asymptomatic pericardial fluid/thickening detected radiographically, tachyarrhythmias, or pericardial tamponade. In addition to its characteristic tendency to spread to hilar and mediastinal lymph nodes, lung cancer may metastasize within the lung in several patterns. One type is lymphangitic carcinomatosis, which usually appears on chest radiography as focal or diffuse reticular or reticulonodular interstitial infiltrates and Kerley B lines, possibly combined with central adenopathy and

Clinical diagnosis and basic evaluation 77

pleural effusions. By high-resolution chest computed tomography (CT), this process characteristically appears as irregular nodular thickening along bronchovascular bundles and interlobular septa, consistent with the role of lymphatics in this form of dissemination.19 Intrapulmonary metastases may also appear as single or multiple nodules/masses in one or both hemithoraces. A management dilemma occurs in patients with otherwise resectable lung cancer who have one or more radiographically indeterminate lung nodules. The differential diagnosis is broad, but includes synchronous lung cancers, granulomatous processes, silicotic nodules, metastatic extrapulmonary malignancies, Wegener’s granulomatosis, and others. An individualized approach to these situations is generally recommended. Lung cancer microembolism to the pulmonary arterial system, a rare form of intrathoracic metastasis, produces dyspnea and is very difficult to diagnose antemortem. Diagnosis has been occasionally accomplished by cytologic examination of blood drawn through a wedged pulmonary artery catheter. Pleural effusion Ten percent of all lung cancers metastasize to the pleura, with adenocarcinoma being the most common.17,20 Malignant pleural effusions due to lung cancer are generally on the same side as the main tumor. They may be moderate to large in size, bloody, and recurrent following thoracentesis. Pleural effusions develop in the setting of malignancy from local effects of the tumor (pleural metastases, lymphatic obstruction, bronchial obstruction with pneumonia or atelectasis, chylothorax), systemic effects (pulmonary thromboembolism, hypoalbuminemia), or as complications of therapy. The main mechanism for malignant pleural effusion formation is altered lymphatic drainage. Metastatic tumor implants on the pleural surface may alter capillary permeability and further increase pleural fluid formation. In most cases, metastatic involvement of the pleura is thought to begin with hematogenous seeding of the visceral pleura followed by subsequent movement and attachment of tumor cells to the parietal pleural surface. Malignant effusions are usually exudative (effusion meets at least one of the following criteria: pleural fluid/ serum total protein ratio >0.5, pleural fluid/serum lactate dehydrogenase [LDH] ratio >0.6, or pleural fluid LDH > two-thirds of the upper limits of normal of the serum). The fluid may appear serous, serosanguinous, or frankly bloody. The initial thoracentesis of a malignant effusion reveals malignant cells 50% of the time.

The cytologic yield increases to 65% and 70% on the second and third attempts, respectively. Pleural fluid cytology is more sensitive than closed pleural biopsy, primarily because pleural metastases tend to be focal and percutaneous biopysy is performed blindly. Pleural biopsy adds very little to the overall diagnostic yield when combined with cytology.21 Therefore, a second thoracentesis is usually performed rather than closed pleural biopsy if malignant effusion is suspected. Low pleural fluid pH (<7.30) and glucose (<60 mg/dl) values predict higher pleural fluid cytology yields, but also predict poor response to pleurodesis and short survival time.22 Malignant cells in pleural fluid indicate T4 or stage IIIB disease in NSCLC and this eliminates further consideration of surgical resection. It is important to remember, however, that the mere presence of a pleural effusion does not categorically preclude surgery for NSCLC. Other conditions that can cause pleural fluid without direct tumor involvement of the pleura include postobstructive pneumonitis/atelectasis, pulmonary embolism, or illnesses unrelated to the tumor, such as congestive heart failure, non-obstructive pneumonia, and cirrhosis. Therefore, the physician must thoroughly evaluate pleural effusion in NSCLC patients with otherwise potentially resectable disease. Unfortunately, series have demonstrated that only 5–10% of lung cancer patients with cytologically negative pleural effusions are ultimately found to have operable disease.23 Superior vena cava syndrome Several well-known syndromes result from regional growth of lung cancer. Obstructed venous flow due to extrinsic compression of the superior vena cava (SVC) by adjacent bronchogenic carcinoma causes the SVC syndrome.24 Overall, approximately 2–4% of patients suffering from bronchogenic carcinoma will develop the SVC syndrome;25 however occurrence is as high as 20% in those with SCLC due to its propensity to develop in the central airways.26 Clinical manifestations result from venous hypertension above the level of the obstruction. Symptoms and signs typically include headache and facial fullness (which may be worse in the recumbent position), swelling and ruddiness of the face, neck, and upper extremities, distended neck veins, and prominent/tortuous collateral venous drainage over the upper torso (Figure 8.1). Chest radiography may reveal mediastinal widening or a right perihilar mass. The differential diagnosis also includes lymphoma, metastatic extrathoracic malignancies, granulomatous mediastinal inflammation/fibrosis, postirradiation fibrosis, and aortic

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Figure 8.1 Tortuous, prominent, collateral venous drainage over the upper torso in superior vena cava syndrome. (Courtesy of JH Ryu MD, Mayo Clinic, Rochester, MN.)

imaging (MRI) in staging is recommended and is superior to CT in determining the extent of local invasion.33 A magnetic resonance angiogram (MRA) is likewise superior to both MRI and CT in assessing vascular involvement.34 The majority of cases of Pancoast’s syndrome are due to NSCLC, but SCLC, metastatic extrapulmonary cancer, and infectious conditions (bacterial, mycobacterial, and fungal) have also been implicated. Tissue diagnosis is recommended and transthoracic needle aspiration is frequently and successfully employed in this regard. Pancoast’s tumors are generally found to be stage IIB, IIIA, or IIIB lesions.

aneurysms. Although the treatment goal remains prompt initiation of palliative chemotherapy or radiation, SVC syndrome is no longer regarded as a medical emergency.27 Diagnostic studies can be safely executed and a tissue diagnosis should be obtained before starting therapy. Overall treatment with radiation and/or chemotherapy is effective in approximately 60% of cases of SVC syndrome due to NSCLC; however recurrence occurs in almost 20%.28 The presence of SVC syndrome is a poor Prognostic indicator for patients with NSCLC, with a median survival of five months.29

Metastatic effects Approximately 40–50% of NSCLC patients present with metastatic disease that precludes surgical resection. SCLC has an even greater propensity to metastasize earlier in its course. Consequently, SCLC is considered a systemic disease at time of diagnosis, even if it appears limited to the chest. Lung cancer dissemination may occur via lymphatic, hematogenous, or interalveolar routes. Metastases to nearly every organ have been described, but the most common sites of involvement are the lung, adrenals, liver, central nervous system, and bone. Clinical manifestations depend upon the extent of specific organ dysfunction induced by metastases. Quoted frequencies of metastases differ depending upon whether initial presentation or autopsy series are cited.

Pancoast’s syndrome Pancoast’s syndrome is characterized by a tumor situated in the extreme apical region of the hemithorax called the superior sulcus, in conjunction with ipsilateral shoulder and medial scapular discomfort. Pancoast initially described the syndrome of shoulder and arm pain in the distribution of the eighth cervical and first and second thoracic nerve trunks, Horner’s syndrome, and ipsilateral hand atrophy and weakness associated with superior pulmonary sulcus tumors.30 Most patients do not have all of these signs and symptoms until late in the course of the disease. Tumor invasion of the adjacent chest wall, brachial plexus, and sympathetic ganglion is the cause for the clinical manifestations. The clinical findings vary depending on the extent to which the adjacent structures are involved. Shoulder pain is the most common symptom, occurring in up to 88% of patients, with arm weakness noted in 40% and Horner’s syndrome in 30%.31 Superior sulcus tumors may manifest on chest radiography as unilateral apical thickening (>5 mm), an apical mass (Figure 8.2), or bony destruction.32 The use of magnetic resonance

Adrenal Adrenal metastases are common in lung cancer. They are usually asymptomatic and initially detected as unilateral adrenal gland enlargement on staging chest CT extended to the upper abdomen. In two series totaling 576 NSCLC patients, 4–7.5% were found to have an isolated unilateral adrenal mass, and approximately 30–40% of the adrenal lesions were found to be malignant.35,36 Adrenal adenomas occur in 2–10% of the general population and typically appear on CT as homogeneous, low attenuation (due to fat content), well-circumscribed lesions <3 cm in diameter.37 The differential diagnosis for benign adrenal enlargement includes adrenal adenomas, nodular hyperplasia, and hemorrhagic cyst. Chemical shift MRI has been shown to be 96% sensitive and 100% specific for distinguishing adenomas,38 and more recently 18F-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG-PET) has been shown to be 93% sensitive and 90% specific for detecting adrenal metastases in patients with known lung cancer.39 A positive result on 18F-FDG-PET, although highly suspicious, does not confirm the presence of adrenal

Clinical diagnosis and basic evaluation 79 (a)

(b)

Figure 8.2 (a) Posteroanterior and (b) lateral chest radiographs, and (c) CT appearance of a large right superior sulcus tumor in a 52-year-old smoker who presented with right shoulder pain. Transthoracic needle aspiration revealed squamous cell carcinoma.

(c)

metastasis, which must be further proven by CT or endoscopic ultrasound-guided needle biopsy before withholding potentially curative resection. Liver Metastatic involvement of the liver is common and usually clinically silent early in the course of disease. Liver metastases are particularly common with SCLC. History and physical exam do not dependably detect liver metastases. Liver involvement may be suggested by abnormalities on the initial staging CT or by elevated liver test values. Advanced liver involvement may be associated with systemic symptoms, such as anorexia, weight loss, and jaundice. Central nervous system Lung cancer is the most common cause for brain metastases, accounting for approximately 70% of cases.40 Clinical and autopsy data indicate that approximately 40% of lung cancer patients will develop brain metastases.17 Small cell and adenocarcinoma are the most common histologic

types of lung cancer to cause brain metastases. Although occasionally asymptomatic, brain metastases usually cause either non-focal symptoms, such as headache (most common), nausea, and vomiting, or focal abnormalities, including seizures, hemi-sensorimotor changes, and cranial nerve deficits. Neurologic symptoms precede lung cancer symptoms in most patients with concurrent disease. Metastases develop more commonly in the cerebral hemispheres, particularly in the parietal and frontal lobes, than in the cerebellum.41 Metastatic lesions are detected by CT or MRI. Central nervous system metastases signal stage IV disease and generally herald an ominous prognosis, but neuro- and radiosurgical advances have resulted in successful treatment of brain metastases leading to improvements in neurologic status and survival.41,42 In SCLC the brain is a common site of relapse and prophylactic cranial irradiation is shown to confer a significant 3-year survival benefit to those patients who experience a complete initial response.43 Other forms of central nervous involvement by metastatic lung cancer include spinal cord metastases and

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leptomeningeal carcinomatosis. Intraspinal lesions usually cause back pain that is worsened by movement, straining, and supine positioning. Neurologic deficits from spinal cord compression, such as sensory defects at or below the level of the lesion, paraparesis or paraplegia, and bowel/bladder incontinence tend to develop quickly, progress rapidly, and be irreversible. In this event, spinal metastases become a medical emergency for which steroids should be starting pending definitive therapy. Leptomeningeal carcinomatosis is uncommon and uniformly predicts a short survival time. Neurologic symptoms may also result from a number of paraneoplastic syndromes, which are discussed below. Bone Skeletal metastases occur in approximately 25–30% of lung cancer patients and are typically found as osteolytic lesions in the vertebral bodies, ribs, and long bones of the arms and legs.17 These lesions usually produce pain or elevations of calcium or alkaline phosphatase.37 Twenty percent of SCLC patients may also have bone marrow involvement, which may not initially be accompanied by clinical or laboratory abnormalities. Bony metastases may be detectable on plain radiographs. If these are negative or non-diagnostic, a planar bone scan, single photon emission computed tomogram (SPECT), or 18F-FDG-PET scan should be obtained. Of these three, 18F-FDG-PET is the most sensitive, but is associated with greatest expense and is not universally available.44,45 Directed MRI of the culprit region remains an alternative as MRI is highly sensitive and specific for bony metastasis, although it has not yet been systematically compared to 18F-FDG-PET in this regard. Paraneoplastic effects Bronchogenic carcinomas are associated with paraneoplastic syndromes more than any other tumor. Ten to twenty percent of lung cancer patients will develop paraneoplastic syndromes.46 These diverse phenomena, most of which are more common with SCLC, result from effects of lung cancer on other organ systems beyond those related to the physical presence of the primary or metastatic lesions. The clinical manifestations are frequently non-specific and are mediated by the ectopic production of biologically active peptides, cytokines, and antibodies. An awareness of the paraneoplastic syndromes is important since they may be the presenting feature of an otherwise difficult to detect lung cancer in its earlier or recurrent stages. With the clinically frustrating exception of the neurologic syn-

dromes, the course of most paraneoplastic syndromes is analogous to that of the underlying lung cancer. Table 8.2 lists the paraneoplastic syndromes associated with lung cancer. The most common paraneoplastic syndromes are discussed below. Hypercalcemia Hypercalcemia is the most frequently encountered paraneoplastic syndrome, occurring in up to 12.5% of patients with lung cancer.47 Lung cancer is the most commonly responsible malignancy, with squamous cell the usual histologic type. Hypercalcemia generally results from tumor production of parathyroid hormone-related peptide (PTHrP).48 Rarely, hypercalcemia is due to osteolytic bony metastases or aberrant elaboration of other cytokines. PTHrP mimics the actions of endogenous parathyroid hormone (PTH), so hypercalcemia results from heightened osteoclastic bone breakdown, decreased bone formation, and decreased renal calcium excretion. The manifestations of hypercalcemia are malaise, weakness, fatigue, abdominal pain, constipation, anorexia, polydipsia, polyuria, confusion, hyporeflexia, and shortened QT interval on electrocardiogram. Coma and death are late manifestations. Diagnosis is made by demonstrating a combination of increased serum ionized calcium level (or disproportionate increase in total serum calcium relative to the serum albumin), normal or low PTH level by immunoassay (to rule out primary hyperparathyroidism), and exclusion of other causes of hypercalcemia (granulomatous disorders such as sarcoidosis, hyperthyroidism, adrenal insufficiency, acute renal failure, Paget’s disease, and medications such as thiazide diuretics and vitamin D). It is also very important to rule out bony metastases. PTHrP is detectable by radioimmunoassay. Treatment strategies are volume repletion with normal saline, increased urinary calcium excretion with a loop diuretic such as furosemide, decreased bony resorption with bisphosphanates, calcitonin, or gallium, and treatment of the underlying malignancy. A novel therapeutic approach inhibiting osteoclast activity through the use of an immunologically mediated tumor necrosis factor receptor blockade has effectively inhibited hypercalcemia in a murine model.49 This therapeutic approach has yet to be fully investigated. Hypercalcemia in the setting of lung cancer is generally a late complication occurring in the setting of advanced disease. The median survival after onset of hypercalcemia is two to three months. Syndrome of inappropriate antidiuretic hormone The cardinal manifestation of the syndrome of inappropriate antidiuretic hormone (SIADH) is hyponatremia

Clinical diagnosis and basic evaluation 81

Table 8.2 Paraneoplastic syndromes associated with lung cancer

Endocrine/metabolic Hypercalcemia Syndrome of inappropriate antidiuretic hormone Cushing’s syndrome Gynecomastia Galactorrhea Acromegaly Carcinoid syndrome Hyperthyroidism Hypercalcitoninemia Hyperglycemia Hypoglycemia Hypouricemia Cachexia/anorexia Cutaneous Clubbing/hypertrophic osteoarthropathy Dermatomyositis Acanthosis nigricans Erythema gyratum repens Hyperpigmentation Urticaria Vasculitis Pruritis Basex’s syndrome (acrokeratosis) Tylosis Erythroderma Acquired ichthyosis Erythema annulare centrifugum Sign of Leser–Trelat Musculoskeletal Polymyositis Myopathy Neurologic Lambert–Eaton myasthenic syndrome Peripheral neuropathy Cerebellar degeneration Limbic encephalitis Polyradiculopathy Myelopathy Opsoclonus/myoclonus Dysautonomia Retinopathy (Continued)

Table 8.2 Continued

Hematologic Anemia Polycythemia Hypercoagulable state Migratory thrombophlebitis Disseminated intravascular coagulation Non-bacterial thrombotic endocarditis Leukocytosis/leukemoid reaction Dysproteinemia Eosinophilia Thrombocytopenia purpura Renal Glomerulonephritis Tubulointerstitial disorders Nephrotic syndrome Modified from references 37 and 46.

due to the inappropriately sustained ectopic production of arginine vasopressin (AVP; antidiuretic hormone), which acts on the distal renal tubule to promote free-water conservation. Small cell is almost always the underlying lung cancer histologic type.50 SIADH can occur with equal frequency in limited and extensive SCLC and may produce symptoms in 5% of patients.46 What, if any, prognostic significance SIADH may have is unclear, although a recent study suggested a slightly worse survival in those patients with limited stage SCLC and SIADH when compared with those without SIADH.51 This is in contrast to earlier studies that found no difference in responsiveness to chemotherapy or survival in patients with SCLC and SIADH in comparison to those without SIADH.50,52 Clinical manifestations of hyponatremia are due to cerebral edema and occur more in relation to the rate of fall of the serum sodium rather than to the absolute serum sodium level. Because the hyponatremia usually develops slowly in SIADH, many patients are asymptomatic at presentation. Early symptoms include fatigue, weakness, nausea, and anorexia. The diagnostic criteria for SIADH are hyponatremia, serum hypoosmolality (<275 mosm/kg), inappropriately increased urine osmolality (>200 mosm/kg), natriuresis (urine sodium >20 mEq/l), clinical euvolemia, and the absence of renal, adrenal, and thyroid dysfunction. Central nervous system disorders, other pulmonary lesions (notably pneumonia), and drugs (including cyclophosphamide, tricyclic antidepressants, thiazide diuretics, morphine, and vincristine) can also cause SIADH.

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Asymptomatic or mildly symptomatic patients may be treated with restriction of water intake to less than 1 liter per day (although sustained compliance is difficult) and demeclocycline (which gradually blocks the action of AVP on the kidney). More serious symptoms, such as seizures, cognitive decline, and mental status changes, or more profound hyponatremia (serum sodium <120 mEq/l), should be treated with normal (0.9%) saline and a loop diuretic. Use of normal saline alone may actually decrease the serum sodium concentration so a loop diuretic must be added. The use of hypertonic (3%) saline is rarely indicated. The goal should be to raise the serum sodium at a maximum rate of 2 mEq/l/hour (maximum 20 mEq/l/day) to a target of 120–125 mEq/l. More aggressive sodium correction may theoretically result in central pontine myelinolysis, a devastating central neurologic insult usually resulting in death. Ectopic adrenocorticotropic hormone syndrome Cushing’s syndrome describes a constellation of findings due to excess glucocorticoid production. Approximately 80% of adrenocorticotropic hormone (ACTH)-dependent cases of Cushing’s syndrome are due to Cushing’s disease – an ACTH-secreting tumor of pituitary origin. The remaining cases are due primarily to ectopic ACTH or corticotropin-releasing hormone (CRH) production, usually by bronchial carcinoid tumors, but also occurring as a result of thymic carcinoid, gastrinoma, pheochromocytoma, and small cell carcinoma.53 Ectopically produced ACTH directly stimulates adrenal glucocorticoid release, while CRH triggers ACTH release from the pituitary. Slowly growing carcinoid tumors may be accompanied by the classic features of Cushing’s syndrome, including truncal weight gain, moon facies, hypertension, purplish cutaneous striae, hirsutism, glucose intolerance, and proximal muscle weakness. Cushing’s manifestations in more rapidly growing SCLC are usually limited to weight loss, hypertension, edema, weakness, poor skin integrity, hypokalemic alkalosis, and glucose intolerance. Overall, less than 5% of SCLC patients develop Cushing’s syndrome46 and its occurrence predicts a shorter survival time, perhaps due to the co-morbidities induced by glucocorticoid excess. An elevated 24-hour urinary free cortisol level (four or more times the upper limit of normal) and failure to suppress cortisol during lowdose dexamethasone challenge generally confirm the presence of Cushing’s syndrome. Late-night salivary cortisol levels have been shown to have high diagnostic sensitivity and specificity for Cushing’s syndrome and

may in the future replace urinary free cortisol or lowdose dexamethasone suppression as a first-line screening test.54 The diagnosis is at times problematic as tumors responsible for Cushing’s syndrome may have variable secretory activity and, especially pulmonary carcinoids, may be suppressible with low-dose dexamethasone. Treatment options include resection (carcinoidtumors),chemotherapy(SCLC),bilateraladrenalectomy, or medical suppression of adrenal glucocorticoid production with ketoconazole, aminoglutethimide, etomidate, or metyrapone. Neurologic syndromes There are several stereotypic neurodegenerative syndromes that occur primarily in SCLC patients. These paraneoplastic syndromes are distinct from the nonfocal neurologic dysfunction induced by systemic effects of cancer. They are felt to be sequelae of autoimmune phenomena that can involve any level(s) of the nervous sytem (brain, cranial nerves, spinal cord, peripheral nerves, neuromuscular junction, and muscle). The proposed pathogenetic sequence begins with the ectopic expression by tumor cells of antigens similar to those normally expressed in the nervous system. The shared antigen is sensed as foreign and an immune response ensues, causing nervous system injury and clinical deficits.55,56 In support of this mechanism are the observations that these syndromes are associated with specific detectable antibodies, nervous system injuries are strikingly limited to specific cell types, deposits of immunoglobulin have been demonstrated in areas of neuronal cell loss, and the characteristic antibodies are made in the central nervous system by autoreactive lymphocytes. The prototypic process of the autoantibody pathogenetic mechanism is the Lambert–Eaton myasthenic syndrome (LEMS). However, not all patients with clinically similar syndromes have detectable autoantibodies, attempts to induce similar syndromes in animals with passive immunoglobulin transfer or immunization with the culprit antigen have been largely unsuccessful, and immunosuppressants are not usually effective treatments. Our understanding of these syndromes continues to evolve. Lambert–Eaton myasthenic syndrome Proximal muscle weakness, hyporeflexia, and autonomic dysfunction (dry mouth, erectile dysfunction, constipation, blurred vision) characterize LEMS. The pathognomonic electromyographic finding is a marked increase of the compound muscle action potential following high rates of nerve stimulation. Similarly, augmented strength and reflexes can be demonstrated on

Clinical diagnosis and basic evaluation 83

physical exam after maximal contraction of the involved muscle groups. Clinical manifestations are due to antibodies to P/Q type voltage-gated calcium channels expressed on the presynaptic cholinergic synapses of peripheral nerves that interfere with the release of acetylcholine.57 These voltage-gated calcium channels also appear on SCLC cells. Treatments of potential benefit include 3,4-diaminopyridine (increases presynaptic calcium influx), pyridostigmine (inhibits acetylcholinesterase), oral immunosuppressive agents such as corticosteroids, plasma exchange, intravenous immunoglobulin, and treatment of the underlying tumor. Approximately one-third to one-half of LEMS patients will improve with treatment of the underlying SCLC. However, not all patients with LEMS have an identifiable underlying malignancy. Antineuronal nuclear autoantibodies-1-associated (ANNA-1) syndromes ANNA-1, also known as anti-Hu antibodies, are IgG antibodies that recognize a family of nuclear mRNA binding proteins expressed in SCLC cells and neurons of the central and peripheral nervous systems. These antibodies are distinct from the autoantibodies of systemic lupus erythematosis, and whether ANNA-1 antibodies have a pathogenetic role in the neurologic manifestations remains unclear. Seropositivity for ANNA-1 is associated with a diverse set of neurologic disorders that can occur in varying combinations.58 Lucchinetti and colleagues59 reported on the wide spectrum of neurologic and oncologic findings in 162 ANNA-1 seropositive patients. Twice as many women were afflicted as men. By the end of follow-up, a malignancy had been detected in 142 patients (88%), with 81% having SCLC. Of the patients with SCLC, 17 developed at least one other malignancy. Neurologic signs associated with ANNA-1, in decreasing frequency, were neuropathy (sensory > mixed somatic > autonomic > motor), cerebellar ataxia, limbic encephalitis (neurocognitive and neurobehavioral deficits), polyradiculopathy, LEMS, myopathy, myelopathy, opsoclonus/ myoclonus, motor neuronopathy, brachial plexopathy, and aphasia. Gastrointestinal dysmotility occurred in 38 (28%) patients, as manifested primarily by gastroparesis and intestinal pseudoobstruction due to involvement of the myenteric plexus. The neurologic manifestations preceded the cancer diagnosis in 96% of patients, and usually progressed in a subacute manner. None of the 49 patients who received immunosuppressant therapy (steroids, plasma exchange, intravenous immunoglobulin, or cyclophosphamide) experienced

neurologic improvement. Somewhat ironically, ANNA-1 seropositivity is associated with more limited stage SCLC at presentation, higher complete tumor response to chemotherapy, and longer survival.60 Patients with unexplained neurologic findings, ANNA-I positivity, and a history of smoking should undergo a thorough search for SCLC, including a chest CT with contrast. If evidence of SCLC is not clearly identified by CT the addition of an 18F-FDG-PET scan should be considered as the combination of CT and 18F-FDG-PET has been shown in one small series to be 100% sensitive for tumor detection.61 Five to fifteen percent of SCLC patients may be ANNA-1 seropositive without neurologic findings. Other neurologic paraneoplastic syndromes Type 2 antineuronal nuclear autoantibodies (ANNA-2), also known as anti-Ri antibodies, are linked with opsoclonus/myoclonus (opsoclonus are involuntary, conjugate, arrhythmic high-amplitude, saccadic eye movements) in breast cancer. Paraneoplastic cerebellar degeneration is associated with a specific anti-Purkinje cell antibody called anti-Yo (PCA 1) in females with breast and gynecologic malignancies. Similar syndromes can occur in SCLC and NSCLC, but lung cancer patients are typically, although not always, ANNA-2 or anti-Yo seronegative. Cancer-associated retinopathy is a rare complication of SCLC, felt to be due to detectable antibodies directed at the retinal photoreceptor layer or ganglion cells. SCLC is also strongly associated with other antineuronal autoantibodies such as collapsing response-mediating protein-5 (CRMP-5), which has yet to be directly associated with a discrete clinical syndrome. It has been suggested that abnormalities identified on autoantibody paraneoplastic panels may serve best to predict the underlying neoplasm rather than a specific neurologic syndrome.62 Other paraneoplastic syndromes Clubbing of the fingers and toes is characterized by loss of the angle between the base of the nail bed and cuticle, rounded nails, and enlargement of the digit tips. Hypertrophic osteoarthropathy (HPO) is a painful, proliferative periostitis that classically involves long bones of the arms and legs. The affected bones reveal periosteal new bone formation on plain radiographs and increased, symmetric uptake on radionuclide studies. Clubbing and HPO are rare entities that can occur together or as isolated findings. The cause(s) remains unknown; however recent data suggest that platelet microthrombi with subsequent release of platelet-derived and vascular

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endothelial growth factors may play a role in the development of clubbing.63 Clubbing and HPO can occur in conjunction with bronchogenic carcinoma, as well as a variety of cardiopulmonary suppurative processes (bronchiectasis, cystic fibrosis, empyema, subacute bacterial endocarditis), usual interstitial pneumonitis/ idiopathic pulmonary fibrosis, pulmonary arteriovenous malformations, congential cyanotic heart disease, inflammatory bowel disease, and cirrhosis. The potential association between the inflammatory myopathies and lung cancer remains to be fully defined.64 Similarly, it is unclear how thoroughly the physician should search for malignancy in patients with unexplained venous thromboembolism. A prospective randomized trial of 201 patients with idiopathic venous thromboembolism65 identified a 10% incidence of occult malignancy in the extensively screened cohort. Over a two-year follow-up, 9.8% of patients in the control group subsequently developed symptomatic malignancy. Overall malignancies were detected earlier and at an earlier stage in the extensively screened group, although a significant survival benefit could not be demonstrated. Currently no professional organization recommends extensive screening for malignancy in the setting of idiopathic venous thromboembolism. A prudent strategy may be to maintain a low threshold of suspicion for malignancy when venous thromboembolism develops without conventional risk factors, and to proceed with additional testing as directed by history, physical exam, and routine initial investigation.

PHYSICAL EXAMINATION A careful physical exam is a vital component of the lung cancer evaluation as it may provide important diagnostic, prognostic, and staging clues. General appearance may be normal or may reveal debilitation, cachexia, lethargy, pallor, jaundice, fever, or significant comorbidities. Blood pressure irregularities can be seen in conjunction with neurologic or adrenal paraneoplastic phenomena. Hoarseness suggests recurrent laryngeal nerve compromise. Respiratory system examination should be conducted in an orderly manner. On inspection, tachypnea may signal painful rib metastases, pleural effusions, or postobstructive pneumonia, while expiratory prolongation is consistent with underlying COPD. Signs of venous hypertension limited to the head, neck, and arms are seen with SVC syndrome, while jugular venous hypertension and pulsus paradoxus are signs of pericardial

tamponade from metastatic disease. Pain may cause the patient to favor the upper extremity ipsilateral to a superior sulcus tumor. Neck palpation may yield evidence of spread to supraclavicular lymph nodes. Focal rib tenderness implies metastases. Direct extension of lung cancer to the chest wall is rarely palpable. The combination of percussible dullness, diminished breath sounds, and reduced fremitus suggests pleural effusion, hemidiaphragm dysfunction due to phrenic nerve entrapment, or postobstructive pneumonitis/atelectasis. Bronchial breath sounds and increased fremitus indicate consolidation with patent proximal airways. Focal wheezing is detected with central airway compromise by an endobronchial tumor or extrinsic compression, generalized wheezing with COPD. Concurrent interstitial lung diseases, such as asbestosis, may be heralded by characteristic Velcro-type inspiratory crackles. Depending on their distribution, rubs may be due to venous thromboembolic events or metastatic pericardial or pleural involvement. The remainder of the exam is equally important. Pertinent skin findings include cutaneous metastases, typically over the torso and scalp, and Basex’s syndrome, which is hyperkeratosis of the acral regions. Acanthosis nigricans, brown velvety plaques of the groin, back of neck and axillae, may be paraneoplastic phenomena, but are more commonly seen with obesity and diabetes. The differential diagnosis for bony pain in the cancer setting includes skeletal metastases and HPO. Liver metastases may be palpable. A thorough nervous system examination is crucial, especially in patients with headache, sensorimotor complaints, and back pain. Unilateral lower extremity swelling, tenderness, and erythema may accompany deep venous thromboses. The history and physical exam findings can be combined to estimate general health status, such as by the Karnofsky (Table 8.3) or Eastern Cooperative Oncology Group (ECOG, Table 8.4) performance scores.66,67 These clinical indices provide a convenient framework to rate the impact of the lung cancer and comorbidities on the patient. Performance status has been reproducibly shown to be an important prognostic variable in NSCLC and SCLC, and usually influences treatment decision-making.

IMAGING Standard chest radiograph The standard posteroanterior and lateral chest radiograph is usually the first test to suggest bronchogenic

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Table 8.3 Karnofsky Performance Scale (modified from Mor et al66) Definition

Percent

Able to carry on normal activity and to work; no special care needed

100 90 80

Unable to work; able to live at home; cares for most personal needs; a varying amount of assistance is needed

70 60 50

Unable to care for self; requires equivalent of institutional or hospital care; disease may be progressing rapidly

40 30 20 10

Criteria

Normal; no complaints; no evidence of disease Able to carry on normal activity; minor signs or symptoms of disease Normal activity with effort; some signs or symptoms of disease Cares for self; unable to carry on normal activity or to do active work Requires occasional assistance but is able to care for most of needs Requires considerable assistance and frequent medical care Disabled; requires special care and assistance Severely disabled; hospitalization is indicated, although death may not be imminent Very sick; hospitalization necessary; active supportive treatment necessary Moribund; fatal processes progressing rapidly

Table 8.4 Eastern Cooperative Oncology Group Performance Scale (from Oken et al67) Performance status

Definition

0 1

Fully active; no performance restrictions Strenuous physical activity restricted; fully ambulatory and able to carry out light work Capable of all selfcare but unable to carry out any work activities. Up and about >50% of waking hours Capable of only limited selfcare; confined to bed or chair >50% of waking hours Completely disabled; cannot carry out any selfcare; totally confined to bed or chair

2 3 4

carcinoma, and it helps to assess the intrathoracic extent of cancer, guides subsequent work-up, and identifies simultaneous thoracic disease.68 The spectrum of possible findings is broad, but the most common are a localized opacity (nodule or mass), pleural effusion, infiltrate, atelectasis, and adenopathy. Certain radiographic appearances may suggest histologic types of lung cancer, but these generalizations are not absolute. Squamous cell carcinoma usually presents as a large mass centered at or near the hilum, that may cavitate. Due to the central airway origin, up to 50% of patients with squamous cell carcinoma will present with endobronchial obstruction with postobstructive pneumonia or atelectasis.69 SCLC may also present as a rapidly enlarging central mass with contiguous hilar and mediastinal involvement. Only 5–10% of SCLCs present as peripheral lung lesions. Adenocarcinoma typically arises

peripherally as a solitary nodule or mass. Large cell carcinoma is characteristically a large peripheral mass. BAC may appear as a nodule or an alveolar infiltrate that can be diffuse. The drawbacks of plain chest radiography include lack of specificity and resolution limitations. Lesions smaller than 2–3 mm are not reliably detectable and the miss rate for lesions less than 2 cm may exceed 50%.70 Regions obscured by the heart, clavicles, and diaphragm may be particularly difficult to interpret. Estimates are that chest radiography is 70–80% accurate in the overall detection of lung cancer, 50–60% sensitive in the detection of hilar adenopathy, and less than 50% sensitive in the detection of mediastinal adenopathy.71 Studies using commercially available computer-aided diagnostic software to improve the sensitivity of digital chest radiographs show modest improvements in nodule detection.72

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Computed tomography CT greatly enhances the imaging of bronchogenic carcinoma by providing further definition of the primary lesion’s appearance, detecting concurrent parenchymal or pleural disease missed by plain chest radiography, demonstrating lymphangitic spread of malignancy, guiding diagnostic maneuvers, and evaluating hilar and mediastinal lymph node metastases. CT also helps in the evaluation of distant metastases by the routine practice of extending the examination to include the liver and adrenals. The delineation by CT of the relation of bronchogenic carcinoma to surrounding structures is particularly important since these findings significantly influence prognosis and, in the case of NSCLC, surgical options. However, the resolution limitations of CT in this regard must be acknowledged. Consensus calls for intrathoracic lymph nodes larger than 1 cm in the short axis dimension to be considered abnormal by CT; however, using this criterion CT is only 57% sensitive and 82% specific in identifying hilar and mediastinal lymph metastases.73 The sensitivity of CT suffers from microscopic lymph node metastases, while the specificity is influenced by benign causes for lymphadenopathy, such as reactive hyperplasia, granulomatous inflammation, and anthracosis. CT also has difficulties in accurately diagnosing chest wall or mediastinal structure invasion, detecting endobronchial lesions, and differentiating tumor from adjacent atelectasis or pneumonia. Hence, CT is not a substitute for histologic information and patients must not be denied surgery for NSCLC simply on CT findings without tissue confirmation. Solitary pulmonary nodule Solitary pulmonary nodule (SPN) is a common clinical radiologic dilemma. Defined as a singular rounded lesion entirely surrounded by normal lung parenchyma and without associated lymphadenopathy, an SPN may be caused by malignant and benign processes (Table 8.5).74 The majority of SPNs are benign. Most malignant SPNs are clinical stage I bronchogenic carcinomas. SPNs are usually incidental findings on plain chest radiographs or CTs obtained for other purposes. The questions become whether the SPN is benign or malignant, and whether it should be observed, biopsied, or removed. The evaluation begins, if possible, with review of previous chest radiographs. A nodule that has been radiographically stable for at least two years is by definition benign, and no further maneuvers are necessary. A steadily growing nodule is considered malignant and should be immediately resected. When

Table 8.5 Causes of solitary pulmonary nodules (from Midthun et al74)

Infectious granuloma Tuberculosis Histoplasmosis Coccidiomycosis Bronchogenic carcinoma Metastatic cancer Breast Head and neck Colon Renal cell Sarcoma Germ cell Bronchial carcinoid Hamartoma Organizing pneumonia/abscess Wegener’s granulomatosis Rheumatoid nodule Arteriovenous malformation Pulmonary infarction Bronchogenic cyst Lipoma Amyloidoma

comparison studies are insufficient, the next step is to assess for calcification in the nodule with CT. Central, concentric, or popcorn calcification patterns are reliable indicators of their benign nature. Eccentric calcification does not rule out malignancy. Thin-section CT images may also detect fat within the nodule, indicative of a hamartoma, which is always benign. Taking advantage of the differences in vascular supply between benign and malignant nodules, Swensen and colleagues75 demonstrated that the level of nodule enhancement detected by thin-section CT after injection of intravenous contrast reliably differentiated benign versus malignant lesions (Figure 8.3). Using 15 Hounsfield units as the threshold for enhancement, sensitivity of this technique for malignancy was 98%. Specificity was just 58%, since some inflammatory and infectious lesions may enhance. The negative predictive value was 96% – if a nodule does not enhance, it is almost always benign. Recently 18F-FDG-PET was compared to nodule enhancement CT and found to have similar sensitivity and superior specificity in differentiating malignant from benign pulmonary nodules, although noduleenhancement demonstrated a negative predictive value

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Figure 8.3 CT images demonstrating enhancement of 87 Hounsfield units (HU) of a left lung nodule after injection of iodinated contrast (31 HU on the precontrast image versus 118 HU on the postcontrast image). The circle within the nodule circumscribes the region used to measure enhancement.

(b)

HU= 31

of 100%.76 The authors concluded that 18F-FDG-PET is preferable to nodule-enhancement CT in evaluating indeterminate pulmonary nodules; however noduleenhancement CT remains a useful tool due to its very high negative predictive value, convenience, and lower cost. If radiologic studies are inconclusive, clinical factors which predict a higher risk of malignancy include advanced age of the patient, smoking history, prior malignancies, and larger nodule size. The patient’s wishes must be considered in the decision-making process. Lesions ≥3 cm in size are malignant in over 90% of cases and should not be observed. If a lesion is not removed and is indeterminate, then it must be observed. Observation typically involves obtaining serial chest CT scans every three months for the first six months, and then every six months for the remainder of two years.77 Serial plain chest radiographs do not reliably detect enlargement of small nodules. If the nodule grows, it must be resected. If the nodule is stable for two years, it is safe to assume that it is benign. With the introduction of helical and multi-detector row CTs the detection of nodules as small as 1–2 mm is becoming common. The Mayo Clinic CT Screening Trial demonstrated that less than 1% of nodules <5 mm in size in patients without a history of cancer proved to be malignant.78 Henschke and colleagues79 further demonstrated that the follow-up interval for nodules <5 mm in size at initial detection could safely be extended to 12 months. The likelihood that an incidentally detected nodule is malignant also depends on known risk factors such as cigarette smoking, as well as radiographic characteristics such as density. With this in mind the Fleischner Society80 has endorsed a statement recommending variable follow-up of small nodules (<8 mm) identified incidentally based on patient risk factors and nodule size at the time of detection. Included in this is a provision for no follow-up of incidentally detected nodules less than or equal to 4 mm in size in low-risk patients.

HU= 118

Ground-glass opacities Recent advances in CT screening for lung cancer (discussed below) have led to increased detection of focal ground-glass opacities (GGOs). A GGO is defined as a hazy area of increased lung attenuation with preserved bronchial and vascular margins (Figure 8.4).81 These features may be the result of interstitial thickening, air space filling or partial collapse, or increased capillary blood flow; alternatively they may be seen as a feature of normal exhalation. As such, GGO is a non-specific finding which may be caused by a variety of infectious, inflammatory, and neoplastic processes.82,83 A recent series84 demonstrated that GGOs with no concomitant solid component will represent malignancy approximately 20% of the time; however with serial follow-up almost 40% will regress or disappear spontaneously. In the same series, GGOs with a concomitant solid component represented malignancy approximately 30% of the time; however up to 50% regressed or disappeared spontaneously. Regression, when present, occurred within the first 90 days of follow-up in the vast majority of cases. Malignant and premalignant lesions are most commonly BAC, adenocarcinoma, and atypical adenomatous hyperplasia.85 Female gender, spiculated border, a concomitant solid component, and size greater than 1 cm appear to be risk factors for malignancy, whereas an elevated serum eosinophil count may predict a benign etiology. When malignant, tumor doubling times vary widely and may be as long as 1486 days for some BACs.86 Frequent spontaneous regression, relatively high malignancy rates, and long doubling times all make management decisions for GGOs problematic, and currently no specific guidelines exist for the follow-up or management of GGOs. Based on available data it may be reasonable to biopsy GGOs that persist beyond 90 days and are greater than 1 cm in size or have other concerning characteristics. Serial follow-up, if elected, should continue beyond five years before determining that an identified GGO does not represent malignancy.

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Figure 8.4 Chest CT demonstrating a ground-glass opacity measuring 12 × 7 mm (circled). Note the preservation of underlying vascular and interstitial structures.

CT lung cancer screening Five-year survival for stage I lung cancer approaches 70%; however <20% of lung cancers are detected at this early stage. That the vast majority of these early stage lung cancers are asymptomatic and identified incidentally on a radiograph or CT obtained for other purposes has raised tremendous interest in devising a rational method to screen for lung cancer radiographically, similar to the way a mammogram is used to screen for breast cancer. Early screening trials conducted in the 1970s using chest radiography and sputum cytology demonstrated a higher incidence rate, resectability, and survivorship among the intensively screened group, but failed to show a mortality benefit (summarized in reference 87). A number of more recent studies investigating the use of low-dose CT have shown an ability to detect earlier stage cancers; however, they have also shown high false-positive rates with indeterminate nodules identified in up to 70% of participants.88,89 Recent five-year prospective data collected on over 1500 highrisk participants suggest that overdiagnosis rather than earlier diagnosis may be playing a role in the use of CT screening, and did not demonstrate a mortality benefit.90 Conversely, a recently reported multicenter study91 enrolling over 31 000 patients over ten years identified 484 lung cancers, 85% of which were stage I. For those patients diagnosed at stage I, the estimated ten-year survival rate was 88%, and 92% for those who underwent surgical resection within one month of diagnosis. At this time no professional organization recommends screening for lung cancer.

F-fluoro-2-deoxy-D-glucose positron emission tomography Accurate staging of NSCLC is essential to determine appropriate therapy and estimate prognosis. Evaluation of mediastinal nodal disease and extrathoracic metastasis is crucial in this regard due to their impact on operative candidacy and potential surgical cure. As discussed above, the accuracy of CT for predicting mediastinal nodal metastasis is not ideal. 18F-FDG-PET is a radionuclide test that involves injection of the radioisotope 18 F-fluorodeoxyglucose (18F-FDG). Tissues with high metabolic activity, such as high-grade neoplasms, demonstrate increased glucose uptake relative to normal tissues and will show increased isotope deposition. A meta-analysis of 18 studies found 18F-FDG-PET to have a sensitivity of 84% and specificity of 89% when investigating the mediastinum for metastases (Figure 8.5).73 In lymph nodes smaller than 1 cm specificity may be as high as 95%, although sensitivity is lower.92 18F-FDG-PET also increases detection of extrathoracic metastases (Figure 8.6), identifying unsuspected distant metastases in as many as 28% of patients with stage III disease in one series,93 and reducing by 20% non-therapeutic thoracotomies in a series enrolling patients with stages IA–IIIA NSCLC.94 18F-FDG-PET imaging has been shown to be superior to conventional imaging for identifying tumor recurrence.95 False-positive results may be seen with various inflammatory and infectious processes such as sarcoidosis, pulmonary Langerhans cell histiocytosis, and mycobacterial and fungal diseases. False-negative results may occur with low-grade neoplastic processes such as BAC and bronchial carcinoid tumors. Because of the occasional false-positive findings potentially metastatic sites should be proven by biopsy when clinically and technically feasible.96 Magnetic resonance imaging MRI does not have a routine role in the evaluation of lung cancer. However, its superiority over CT in distinguishing tumor abutment versus invasion of chest wall, vertebral, and mediastinal structures makes MRI a useful adjunct in situations such as superior sulcus tumors and possible neuroforaminal encroachment. The magnetic resonance angiogram (MRA) is the study of choice to investigate vascular invasion. Other nuclear medicine studies In NSCLC patients with marginal pulmonary function, quantitative ventilation-perfusion (V/Q) lung scans can be used to assess candidacy for lung resection.

Clinical diagnosis and basic evaluation 89 (a)

(c)

Figure 8.5 18F-FDG-PET scan with CT fusion demonstrating a primary adenocarcinoma in the left upper lobe (a), with contralateral hilar metastasis (b). (c) Coronal 18F-FDG-PET without CT fusion, demonstrating no extrathoracic involvement. Transbronchial needle aspirate of the right hilar lymph node confirmed metastatic adenocarcinoma with stage IIIB NSCLC assigned. (See color plate section, page xiii)

(b)

The fraction of total ventilation or perfusion from the contralateral lung is multiplied by the preoperative forced expiratory volume in 1 second (FEV1) to predict postoperative FEV1 for patients undergoing pneumonectomy. A postoperative FEV1 of 40% of predicted suggests the patient should tolerate resection from a pulmonary perspective.97 Bone scan and 18F-FDG-PET are useful in investigating bony metastases in patients with bone pain, hypercalcemia, increased alkaline phosphatase, and/or pathologic fractures. Of these three techniques, 18F-FDG-PET is the most sensitive and has the additional advantage of identifying other areas of intra- and extrathoracic metastases. Abnormalities identified with these techniques will require further

evaluation by plain radiography or MRI, and, under appropriate clinical circumstances, biopsy.

DIAGNOSTIC TECHNIQUES An accurate tissue diagnosis is an essential early step in the management of lung cancer because of its therapeutic and prognostic import. Biopsy procedures are not always required before surgical therapy, but are conducted in most patients suspected of lung cancer since clinical and radiographic findings are not uniquely assigned to SCLC or NSCLC. Various techniques are available to obtain tissue for cytologic and histopathologic analysis.

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(c)

Figure 8.6 18F-FDG-PET scan with CT fusion demonstrating a primary adenocarcinoma involving the left upper lobe with ipsilateral mediastinal lymph node metastasis (a), and left adrenal mestastasis (b). (c) Coronal 18F-FDG-PET without CT fusion demonstrating mediastinal and extrathoracic (left adrenal) involvement. CT-guided biopsy of the left adrenal confirmed metastatic adenocarcinoma with stage IV NSCLC assigned. (See color plate section, page xiv)

(b)

Sputum examination Sputum cytology Sputum cytology is a non-invasive method to obtain a diagnosis in appropriate situations.98 The yield depends on the ability of the patient to produce acceptable sputum, tumor size, location of the tumor in relation to major central airways, and the skills of the cytopathologist. The average sensitivity is approximately 65%, with sensitivities ranging from 22 to 98% reported.99 Most studies, although not all, show decreased sensitivity for the diagnosis of peripherally based nodules and masses, with an overall sensitivity of 71% for central and 49% for peripheral lesions.99 The appropriate number of specimens to collect remains unclear, but one to three

consecutive early morning samples or a three-day pooled sputum specimen are generally recommended.100 A sputum sample can be obtained spontaneously or induced, and is considered representative if bronchial epithelial cells or alveolar macrophages are present. Overall diagnostic yield appears highest with specimens collected spontaneously, except in the setting of peripherally based cancers where induced specimens appear more informative.101,102 Abnormal findings may also result from concurrent pulmonary infections (false-positives) or unsuspected head and neck cancers. Sputum cytometry Recent data suggest that the yield of sputum cytology may be improved through the use of molecular, genetic,

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and immunocytochemical markers of malignancy. Studies evaluating archived sputum specimens collected as part of lung cancer screening programs have shown that abnormal cells may be identified as early as twenty months prior to the diagnosis of lung cancer using these techniques. Xing and colleagues103 further demonstrated a twenty-fold improvement in sensitivity over sputum cytology alone using automated cytometric techniques. They were able as well to detect severe dysplasia/carcinoma in situ lesions and correctly identified over 70% of peripherally based cancers. A sensitivity of 75% and specificity of 98% has been shown for semiautomated sputum cytometry in the diagnosis of lung cancer in a multinational study.104 These results have sparked interest in the implementation of this technique as part of a co-ordinated lung cancer screening process.

specimens. TBNA should be obtained before sampling other endoscopically visible lesions to avoid false-positive results. Bleeding is a very infrequent complication of TBNA. Autofluorescence bronchoscopy exploits the difference in fluorescence properties between normal bronchial mucosa and that of invasive and pre-invasive disease. The best-known device uses a helium-cadmium laser (442-nm wavelength) and an optical multichannel analyzer in place of the standard white light source, with normal mucosal surfaces having a green coloration whereas premalignant and malignant lesions appear reddish in color. A prospective, multicenter trial demonstrated an increase in the detection of preinvasive disease with the use of autofluorescence by a factor of 2.1 when compared to white light bronchoscopy alone.110 Bronchoscopy in COPD patients confers only a slightly increased risk if obstruction is severe.

Flexible fiberoptic bronchoscopy Flexible fiberoptic bronchoscopy is commonly used for diagnostic and staging purposes. Endoscopically visible abnormalities are approached with traditional biopsy forceps, brushings, and washings. Transbronchial needle aspirations (TBNAs) may also be performed on submucosal tumors or those causing extrinsic bronchial compression. The yield from an endoscopically visible lesion should be in excess of 80%. Peripheral lesions are sampled with fluoroscopically guided transbronchial biopsies, brushings, and washings. Lesion size is the primary determinant of outcome, with yields of 25% reported for malignant lesions under 2 cm, 60–70% for lesions >2cm, and 80% for lesions >4 cm.105 Yield, particularly for lesions <2 cm, may be increased with the use of electromagnetic navigation bronchoscopy, with a recent study demonstrating 74% diagnostic yield for peripheral lesions in this size range.106 Transbronchial lung biopsies should detect lymphangitic spread of malignancy. For staging purposes, bronchoscopy may occasionally detect synchronous lesions, assess proximal extent of tumor, and facilitate sampling of paratracheal, subcarinal, and hilar lymph nodes by TBNA. Traditional TBNA sensitivity is 50%, with a specificity of 90% for mediastinal staging.107 However, guidance using endobronchial ultrasound (EBUS) increased the sensitivity to 94% in one study of 500 patients.108 EBUS also appears superior to CT in differentiating airway tumor infiltration from extrinsic compression.109 Chest CT should be obtained before TBNA to help guide the attempts. Use of 19-gauge needles improves sensitivity by allowing procurement of cytologic and histologic

Transthoracic needle aspiration Peripheral lesions or those with extension to the mediastinum, chest wall, or pleura may also be sampled by fluoroscopically or CT-guided transthoracic needle aspiration (TTNA). Suspicious peripheral lesions are sometimes directly resected for diagnosis and treatment if surgery would be the anticipated maneuver regardless of TTNA results. However, TTNA may be applied when a tissue diagnosis is needed but the patient cannot or will not undergo surgery, the patient is undecided about surgery pending tissue confirmation of cancer, or fiberoptic bronchoscopy was non-diagnostic. Yields above 90% have been reported.111,112 Pneumothorax is the main complication, occurring in up to 30% of cases, yet less than 15% typically require a chest tube. Tumor seeding of the biopsy tract is a very rare complication. Increased risk situations for TTNA include bullous emphysema in the region to be biopsied, lesions located away from the pleural surface, a poorly cooperative patient, and underlying lung disease whose impact would significantly increase if pneumothorax developed. There is a substantial false-negative rate (20–30% of patients with a negative TTNA may have a malignant lesion)37 so indeterminate or negative TTNA results must not be interpreted as a diagnostic endpoint. A repeat TTNA is diagnostic in 35–65% of cases.37 Percutaneous radiologic-guided needle aspiration is used to confirm metastases to liver, bone, and adrenals. Endoscopic ultrasound The linear array echoendoscope was introduced in the mid-1990s and is gaining popularity due to its ability to

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permit fine-needle aspiration of mediastinal abnormalities from a transesophageal approach that are not easily accessed by bronchoscopy or mediastinoscopy. Endoscopic ultrasound (EUS) easily identifies vascular structures and is useful in sampling tissue from inferior and posterior mediastinal (station 8, 9), aortopulmonary window (station 5, 6), and subcarinal (station 7) lymph nodes. Lobar (station 12), interlobar (station 11), and anterior tracheal nodes (station 3) are not well evaluated by EUS. In a study of 26 patients undergoing transesophageal biopsy performed with EUS and fineneedle aspiration the overall sensitivity for the diagnosis of malignancy was 89% and the specificity was 83%, with a positive predictive value of 100% and a negative predictive value of 75%.113 Recent studies further suggest that EUS may be superior to CT and PET in establishing mediastinal staging of NSCLC,114,115 and may be superior to mediastinoscopy in sampling paratracheal and subcarinal nodes.116 Thoracic surgery techniques Cervical mediastinoscopy and anterior mediastinotomy have been the traditional routes by which histologic verification of mediastinal metastases has been obtained. These are safe procedures whose findings may obviate the need for further surgery in NSCLC patients. Cervical mediastinoscopy allows sampling of the right paratracheal and subcarinal nodes, while anterior mediastinotomy accesses the left paratracheal, supra-aortic, and aortopulmonary window nodes.37 It remains controversial whether mediastinal sampling should be routinely performed before all surgery for NSCLC. Many surgeons may forego mediastinoscopy in patients with radiographic T1N0 disease due the relatively low prevalence (5–15%) of nodal metastases in this group. 18F-FDG-PET may have a role in these patients, allowing those without evidence of mediastinal involvement to avoid mediastinal lymph node sampling, although PET combined with CT may still miss up to 5% of mediastinal micrometastases.117 Video-assisted thoracoscopic surgery (VATS) is a more recent, less invasive technique for sampling of indeterminate peripheral nodules, pleural thickening and effusions, and mediastinal/hilar lymph nodes. Scalene or supraclavicular lymph node biopsy is an appropriate diagnostic and staging procedure in the setting of clinically significant enlargement. The patient with a suspicious lesion (enlarging or spiculated nodule) without evidence of metastatic disease may go directly to thoracotomy for definitive diagnosis and treatment.

OVERVIEW OF BASIC EVALUATION The purpose of the basic evaluation is to efficiently and accurately establish the diagnosis and initial extent of lung cancer. Aspects of this process are influenced by local practice biases. The core elements include a careful history and physical exam, posteroanterior and lateral chest radiographs, and basic blood tests, including complete blood count and chemistry profile (especially electrolytes, serum calcium, alkaline phosphatase, glutamic-oxaloacetic transaminase, albumin, total bilirubin, and creatinine).36 While the cost-effectiveness of the blood tests can be debated, they may suggest metastatic disease, paraneoplastic phenomena, or co-morbidities. Chest CT with extension to upper abdominal CT is routinely obtained to define the primary lesion and locoregional extent of disease. 18F-FDG-PET scanning plays an additive role in addressing the solitary pulmonary nodule and should be included when investigating mediastinal and extrathoracic metastases from a known NSCLC. Testing for extrathoracic metastases is pursued as directed by the initial information. Biopsy of suspected metastases may allow simultaneous diagnosis and staging. For peripheral chest lesions the diagnostic options are TTNA, bronchoscopy, VATS, or thoracotomy. It is unclear whether TTNA or bronchoscopy is the better initial choice. TTNA may enjoy a higher yield for smaller lesions, but also a higher complication rate. Bronchoscopy allows for endobronchial visualization and would still be performed at the time of thoracotomy if TTNA were positive. For central lesions or hemoptysis with negative chest film, sputum cytology is also an option, and bronchoscopy is usually favored over TTNA. Additional pulmonary testing may be necessary if surgical resection is considered. Given the common etiologic thread of smoking, it is not surprising that 80–90% of lung cancer patients also have COPD, 20–30% with severe disease.118 Lung resection, incisional pain, medical appliances, and postoperative use of sedatives and analgesics impact negatively on lung function and defense. Preoperative spirometry and diffusing capacity (DLCO) should be obtained. Patients with FEV1 >1.5–2 l, maximal voluntary ventilation (MVV) >50% predicted, and DLCO >60% predicted can proceed to thoracotomy. Patients below these values may need to undergo a more thorough examination that includes quantitative V/Q lung scanning and/or exercise testing with evaluation of maximum oxygen uptake. Although no value categorically precludes surgery, predicted postoperative FEV1 <40% of predicted, hypercapnia (PCO2 >45), or maximal oxygen consumption <10 ml/

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kg/min during exercise testing predicts significant postoperative problems.119 The use of VATS and limited resections have dramatically changed the definition of inoperability due to pulmonary limitations.

FUTURE DEVELOPMENTS Given the dramatic differences in overall lung cancer survival versus those enjoyed with resectable stage I disease, interest will continue to focus on methods of earlier lung cancer detection and more accurate staging. The recent use of spiral CT scanners allows for extremely rapid thoracic imaging at a reduced radiation dose, thereby imparting the benefits of CT sensitivity with the speed and radiation levels of more traditional radiographic imaging. Whether CT screening, alone or in concert with other screening modalities, results in earlier detection and decreased mortality from lung cancer remains to be demonstrated and the results of the National Lung Screening Trial will determine to a great extent whether CT screening is adopted as a viable standard screening modality. Sputum cytometry and autofluorescence bronchoscopy additionally show promise as methods to identify cancerous and precancerous lesions within the central airways early, when directed therapy or resection is most successful. Their role in standardized screening warrants further investigation. In 2007 a five-year randomized surveillance study funded by Cancer Research UK incorporating combined techniques of sputum cytology/cytometry, CT scanning, and autofluorescence bronchoscopy began enrollment and have helped define the role of these techniques in screening for lung cancer. Early reports of serum proteomic patterns being able to distinguish patients with ovarian and prostate cancer from normal controls are exciting, although preliminary. What, if any, role proteomic patterns may play in the detection and diagnosis of lung cancer is one of the most intriguing new areas of investigation in early detection. It is hoped that these new techniques combined with greater participation of patients in prospective clinical trials (currently only 1% of lung cancer patients in the USA are enrolled) will result in improved lung cancer survival rates. REFERENCES 1. Jemal A, Siegel R, Ward E et al. Cancer statistics, 2006. CA Cancer J Clin 2006; 56: 106–30.

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43. Ausperin A, Arriagada R, Pignon JP et al. Prophylactic cranial irradiation for patients with small cell lung cancer in complete remission. Prophylactic Cranial Irradiation Overview Collaborative Group. N Engl J Med 1999; 341: 476–84. 44. Hetzel M, Arslandemir C, Konig H et al. F-18 NaF PET for detection of bone metastases in lung cancer: accuracy, costeffectiveness, and impact on patient management. J Bone Min Res 2003; 18: 2206–14. 45. Schirrmeister H, Glatting G, Hetzel J et al. Prospective evaluation of the clinical value of planar bone scans, SPECT, and (18)F-labeled NaF PET in newly diagnosed lung cancer. J Nucl Med 2001; 42: 1800–4. 46. Patel AM, Davila DG, Peters SG et al. Paraneoplastic syndromes associated with lung cancer. Mayo Clin Proc 1993; 68: 278–87. 47. Burtis WJ. Parathyroid hormone-related protein: structure, function, and measurement. Clin Chem 1986; 4: 1191–8. 48. Bender RA, Hansen H. Hypercalcemia in bronchogenic carcinoma: a prospective study of 200 patients. Ann Intern Med 1974; 80: 205–8. 49. Oyajjobi BO, Anderson DM, Traianedes K et al. Therapeutic efficacy of a soluble receptor activator of nuclear factor KBIgG Fc fusion protein in suppressing bone resorption and hypercalcemia in a model of humoral hypercalcemia of malignancy. Cancer Res 2001; 61: 2572–8. 50. List AF, Hainsworth JD, Davis BW et al. The syndrome of inappropriate secretion of anti-diuretic hormone in small cell lung cancer. J Clin Oncol 1986; 4: 1191–8. 51. Tai P, Yu E, Jones K et al. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) in patients with limited stage small cell lung cancer. Lung Cancer 2006; 53: 211–15. 52. Hainsworth JD, Workman R, Greco A. Management of the syndrome of inappropriate antidiuretic hormone secretion in small cell lung cancer. Cancer 1983; 51: 161–5. 53. Ilias I, Torpy DJ, Pacak K et al. Cushing’s syndrome due to ectopic corticotropin secretion: twenty years’ experience at the National Institutes of Health. J Clin Endocrinol Metab 2005; 90: 4955–62. 54. Arnaldi G, Angeli A, Atkinson AB et al. Diagnosis and complications of Cushing’s syndrome: a consensus statement. J Clin Endocrinol Metab 2003; 88: 5593–5602. 55. Dalmau J, Posner JB. Paraneoplastic syndromes affecting the nervous system. Semin Oncol 1997; 24: 318–28. 56. Rosenfeld MR, Eichen JG, Wade DF et al. Molecular and clinical diversity in paraneoplastic immunity to Ma proteins. Ann Neurol 2001; 50: 339–48. 57. Lennon VA, Kryzer TJ, Griesmann GE et al. Calcium-channel antibodies in the Lambert–Eaton syndrome and other paraneoplastic syndromes. N Engl J Med 1995; 332: 1467–74. 58. Graus F, Keime-Guilbert F, Rene R et al. Anti-Hu-associated paraneoplastic encephalomyelitis: analysis of 200 patients. Brain 2001; 124: 1138–48. 59. Lucchinetti CF, Kimmel DW, Lennon VA. Paraneoplastic and oncologic profiles of patients seropositive for type I antineuronal nuclear autoantibodies. Neurology 1998; 50: 652–7. 60. Graus F, Dalmau J, Rene R et al. Anti-Hu antibodies with small-cell lung cancer: association with complete response to therapy and improved survival. J Clin Oncol 1997; 15: 2866–72.

Clinical diagnosis and basic evaluation 95 61. Linke R, Schroeder M, Helmberger T et al. Antibody-positive paraneoplastic syndromes: value of CT and PET for tumor diagnosis. Neurology 2004; 63: 282–6. 62. Pittock SJ, Kryzer TJ, Lennon VA et al. Paraneoplastic antibodies coexist and predict cancer, not neurological syndrome. Ann Neurol 2004; 56: 609–10. 63. Atkinson S, Fox SB. Vascular endothelial growth factor (VEGF)-A and platelet-derived growth factor (PDGF) play a central role in the pathogenesis of digital clubbing. J Pathol 2004; 203: 721–8. 64. Dalakas MC. Polymyositis and dermatomyositis. Lancet 2003; 362: 971–82. 65. Piccioli A, Lensing AWA, Prins MH et al. Extensive screening for occult malignant disease in idiopathic venous thromboembolism: a prospective randomized clinical trial. J Thromb Haemost 2004; 2: 884–9. 66. Mor V, Laliberte L, Morris JN et al. The Karnofsky Performance Status Scale: an examination of its reliability and validity in a research setting. Cancer 1984; 53: 2002–7. 67. Oken MM, Creech RH, Torney DC et al. Toxicity and response criteria of the Eastern Cooperative Oncology Group. Am J Clin Oncol 1982; 5: 649–55. 68. Karsell PR, McDougall JC. Diagnostic tests for lung cancer. Mayo Clin Proc 1993; 68: 288–96. 69. Midthun D, Jett J. Lung tumors. In: Albert R, Spiro S, Jett J, eds. Comprehensive Respiratory Medicine. London: Mosby, 2004. 70. Quenkel G, Kessels A, Goei R, van Engelshoven J. Miss rate of lung cancer on chest radiograph in clinical practice. Chest 1999; 115: 720–4. 71. Swensen SJ, Brown LR. Conventional radiology of the hilum and mediastinum in bronchogenic carcinoma. Radiol Clin North Am 1990; 28: 521–38. 72. Kakeda S, Moriya J, Sato H et al. Improved detection of lung nodules on chest radiographs using a commercial computer-aided diagnosis system. Am J Roentgenol 2004; 182: 505–10. 73. Toloza EM, Harpole L, McCrory DC. Noninvasive staging of non-small cell lung cancer. Chest 2003; 123: 137–46S. 74. Midthun DE, Swensen SJ, Jett JR. Approach to the solitary pulmonary nodule. Mayo Clin Proc 1993; 68: 378–85. 75. Swensen S, Viggiano R, Midthun D et al. Lung nodule enhancement at CT: multicenter study. Radiology 2000; 214: 73–80. 76. Christensen JA, Nathan MA, Mullan BP et al. Characterization of the solitary pulmonary nodule: 18F-FDG-PET versus nodule-enhancement CT. Am J Roentgenol 2006; 187: 1361–7. 77. Ost D, Fein AM, Feinsilver SH. The solitary pulmonary nodule. N Engl J Med 2003; 348: 2535–42. 78. Midthun DE, Swensen SJ, Jett JR et al. Evaluation of nodules detected by screening for lung cancer with low dose spiral computed tomography. Lung Cancer 2003; 41 (Suppl 2): S40. 79. Henschke CI, Yankelevitz DF, Naidich DP et al. CT screening for lung cancer: suspiciousness of nodules according to size on baseline scans. Radiology 2004; 231: 164–8. 80. McMahon H, Austin JH, Gamsu G et al. Guidelines for management of small pulmonary nodules detected on CT scans: a statement from the Fleischner Society. Radiology 2005; 237: 395–400.

81. Austin JH, Muller NL, Friedman PJ et al. Glossary of terms for CT of the lungs: recommendations of the Nomenclature Committee of the Fleischner Society. Radiology 1996; 200: 327–31. 82. Nagajima R, Yokose T, Kakinuma R et al. Localized pure ground-glass opacity on high resolution CT: histologic characteristics. J Comput Assist Tomogr 2002; 26: 323–9. 83. Collins J, Stern EJ. Ground-glass opacity at CT: the ABCs. Am J Roentgenol 1997; 169: 355–67. 84. Oh J-Y, Kwon S-Y, Yoon H-I et al. Clinical significance of a solitary ground-glass opacity (GGO) lesion of the lung detected by chest CT. Lung Cancer 2007; 55: 73–6. 85. Nakata M, Saeki H, Takata I et al. Focal ground-glass opacity detected by low-dose helical CT. Chest 2002; 121: 1464–7. 86. Aoki T, Nakata H, Watanabe K et al. Evolution of peripheral lung adenocarcinomas: CT findings correlated with histology and tumor doubling time. Am J Roentgenol R 2000; 174: 763–8. 87. Bach PB, Kelley MJ, Tata RC, McCrory DC. Screening for lung cancer: a review of the current literature. Chest 2003; 123: 72–82S. 88. Henschke CI, McCauley DI, Yankelevitz DF et al. Early Lung Cancer Action Project: overall design and findings from baseline screening. Lancet 1999; 354: 99–105. 89. Swensen SJ, Jett JR, Hartman TE, Midthun DE et al. Lung cancer screening with CT: Mayo Clinic experience. Radiology 2003; 226: 756–61. 90. Swensen SJ, Jett JR, Hartman TE et al. CT screening for lung cancer: five-year prospective experience. Radiology 2005; 235: 259–65. 91. International Early Lung Cancer Action Program Investigators; Henschke CI, Yankelevitz DF, Libby DM et al. Survival of patients with stage I lung cancer detected on CT screening. N Engl J Med 2006; 355: 1763–71. 92. Gupta N, Graeber G, Bishop H. Comparative efficacy of positron emission tomography with fluorodeoxyglucose in evaluation of small (< 1 cm), intermediate (1–3 cm), and large (> 3 cm) lymph node lesions. Chest 2000; 117: 773–8. 93. Eschmann SM, Friedel G, Paulsen F et al. FDG PET for staging of advanced non-small cell lung cancer prior to neoadjuvant radio-chemotherapy. Eur J Nucl Med Mol Imaging 2002; 29: 804–8. 94. Reed CE, Harpole DH, Posther KE et al. Results of the American College of Surgeons Oncology Group Z0050 Trial: the utility of positron emission tomography in staging potentially operable non-small cell lung cancer. J Thorac Cardiovasc Surg 2003; 126: 1943–51. 95. Bury T, Corhay JL, Duysinx B et al. Value of FDG-PET in detecting residual or recurrent nonsmall cell lung cancer. Eur Respir J 1999; 14: 1376–80. 96. Pieterman R, van Putten J, Meuzelaar J et al. Pre-operative staging of non-small cell lung cancer with positron-emission tomography. N Engl J Med 2000; 343: 254–61. 97. Kaza AK, Mitchell JD. Preoperative pulmonary evaluation of the thoracic surgical patient. Thorac Surg Clin 2005; 15: 297–304. 98. Mehta AC, Marty JJ, Lee FYW. Sputum cytology. Clin Chest Med 1993; 14: 87–98.

96 Textbook of Lung Cancer 99. Schreiber G, McCrory DC. Performance characteristics of different modalities for diagnosis of suspected lung cancer: summary of published evidence. Chest 2003; 123: 115–28. 100. Ng AB, Horak GC. Factors significant in the diagnostic accuracy of lung cytology in bronchial washing and sputum samples. II. Sputum samples. Acta Cytol 1983; 27: 397–402. 101. Kennedy TC, Proudfoot SP, Piantadosi S et al. Efficacy of two sputum collection techniques in patients with air flow obstruction. Acta Cytol 1999; 43: 630–6. 102. Agusti C, Xaubet A, Monton C et al. Induced sputum in the diagnosis of peripheral lung cancer not visible endoscopically. Resp Med 2001; 95: 822–8. 103. Xing S, Khanavkar B, Nakhosteen JA et al. Predictive value of image cytometry for diagnosis of lung cancer in heavy smokers. Eur Resp J 2005; 25: 956–63. 104. Marek W, Kotschy-Lang N, Muti A et al. Can semi-automated image cytometry on induced sputum become a screening tool for lung cancer? Evaluation of quantitative semi-automated sputum cytometry on radon and uranium workers. Eur Resp J 2001; 18: 942–50. 105. Arroliga AC, Matthay RA. The role of bronchoscopy in lung cancer. Clin Chest Med 1993; 14: 87–98. 106. Gildea TR, Mazzone PJ, Karnak D et al. Electromagnetic navigation diagnostic bronchoscopy: a prospective study. Am J Resp Crit Care Med 2006; 174: 982–9. 107. Harrow EM, Wang KP. The staging of lung cancer by bronchoscopic transbronchial needle aspiration. Surg Clin North Am 1996; 6: 223–35. 108. Herth FJ, Eberhardt R, Vilmann P et al. Real-time endobronchial ultrasound guided transbronchial needle aspiration for sampling of mediastinal lymph nodes. Thorax 2006; 61: 795–8. 109. Herth F, Ernst A, Schultz M et al. Endobronchial ultrasound reliably differentiates between airway infiltration and compression by tumor. Chest 2003; 123: 458–62. 110. Haussinger K, Becker H, Stanzel F et al. Autofluorescence bronchoscopy with white light bronchoscopy compared with

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9

Staging, classification, and prognosis Michael Dusmet, Peter Goldstraw Contents Introduction • The staging system • The staging process • The staging tests • Restaging after induction chemotherapy • Other prognostic indicators • Prognosis

INTRODUCTION It is logical that this chapter should fall between the preceding one on diagnosis and evaluation and those that follow on the treatment modalities for non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). At its most simplistic, ‘staging’ is the process by which the clinician examines and describes the local, regional, and distant extent of the cancer. This precise information is then used to determine the appropriate therapy for a patient diagnosed to have lung cancer. However, staging should not be thought of as a set of investigations that are performed between diagnosis and treatment. Many of the tests that are undertaken to establish the diagnosis, such as chest radiography, bronchoscopy, and pleural aspiration cytology, provide valuable information as to stage. Often the choice of test by which to establish the diagnosis will be made on the basis of the clinician’s assessment of the probable stage of the disease. In this context, obviously taking into account the financial cost and the potential morbidity of every procedure, it is desirable to undertake first the test that will prove the highest stage. For example, if a patient has a lung lesion and a probable adrenal metastasis, biopsy of the adrenal will, if positive, provide both a tissue diagnosis of cancer and the stage (M1).Tests undertaken to decide stage proceed in parallel with those required to establish the diagnosis and others to assess patient fitness for possible treatment options, often interweaving and providing information across these categories. Tests may have to be repeated if undertaken without sufficient foresight to look beyond the diagnosis and consider the consequential issues of treatment. Sometimes treatment may be recommended after staging and before a firm diagnosis. A surgeon may ‘stage’ a patient and recommend thoracotomy with only the strong clinical–radiographic suspicion of lung cancer and without pursuing the diagnosis to a cytologic or histologic conclusion. In such circumstances the surgeon will establish the diagnosis as the

first step at thoracotomy using rapid, ‘frozen section’ histology prior to proceeding with treatment by pulmonary resection. Thus staging has several objectives, some patient orientated and some disease centered. Precise staging will allow the clinician to offer the individual patient the best treatment, on the basis of the understanding of prognosis that derives from the stage. Staging allows clinicians to evaluate the results of different treatment regimens and to exchange and compare them between different centers. This also allows new treatment strategies to be assessed. Finally it allows us to evaluate in an on-going manner the results of staging modalities. We will consider the separate aspects of staging: the ‘staging system’, the ‘staging process’, and the ‘staging tests’.

THE STAGING SYSTEM The International Staging System (ISS) for lung cancer is the TNM Classification of Malignant Tumors, administered by the International Union Against Cancer (UICC).1 This provides a recognized shorthand to describe the extent of the disease, in which the T descriptor indicates the extent of the primary tumor, the N descriptor the extent of lymph node involvement, and the M descriptor the presence or absence of distant metastases. For each descriptor, advancing numeric subscripts are allocated for progressively advancing disease. The latest revision of the ISS was published in 1997,2,3 and integrated into the sixth edition of the UICC TNM Classification of Malignant Tumors manual in 2002.4 The next revision of the staging system is due to be published early in 2009. The descriptors as presently defined are listed in Table 9.1. A more precise definition of the boundaries and definitions can be found in another article by Dr Mountain.5 The definition of the great vessels includes the aorta, the vena cava,

98 Textbook of Lung Cancer Table 9.1 TNM descriptorsa

Primary tumor (T) TX Primary tumor cannot be assessed, or tumor proven by the presence of malignant cells in sputum or bronchial washings but not visualized by imaging or bronchoscopy T0 No evidence of primary tumor Tis Carcinoma in situ T1 Tumour ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchusb (i.e. not in the main bronchus) T2 Tumor with any of the following features of size or extent: • >3 cm in greatest dimension • involves main bronchus, ≥2 cm distal to the carina • invades the visceral pleura • associated with atelectasis or obstructive pneumonitis that extends to the hilar region but does not involve the entire lung. T3 Tumor of any size that directly invades any of the following: chest wall (including superior sulcus tumors), diaphragm, mediastinal pleura, parietal pericardium; or tumor in the main bronchus <2 cm distal to the carina, but without involvement of the carina; or associated atelectasis or obstructive pneumonitis of the entire lung T4 Tumor of any size that invades any of the following: mediastinum, heart, great vessels, trachea, esophagus, vertebral body, carina; or tumor with a malignant pleural or pericardial effusion,c or with satellite tumor nodule(s) within the ipsilateral primary-tumor lobe of the lung Regional lymph nodes (N) NX Regional lymph nodes cannot be assessed N0 No regional lymph node metastasis N1 Metastasis to ipsilateral peribronchial and/or ipsilateral hilar lymph nodes, and intrapulmonary nodes involved by direct extension of the primary tumor N2 Metastasis to ipsilateral mediastinal and/or subcarinal lymph node(s) N3 Metastasis to contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s) Distant metastasis (M) MX Presence of distant metastasis cannot be assessed M0 No distant metastasis M1 Distant metastasis presentd a

Reproduced with kind permission of Dr CF Mountain and the Editor of Chest.2 The uncommon superficial tumor of any size with its invasive component limited to the bronchial wall, which may extend proximal to the main bronchus, is also classified T1. c Most pleural effusions associated with lung cancer are due to tumor. However, there are a few patients in whom multiple cytopathologic examinations of pleural fluid show no tumor. In these cases, the fluid is non-bloody and is not an exudate. When these elements and clinical judgement dictate that the effusion is not related to the tumor, the effusion should be excluded as a staging element and the patient’s disease should be staged T1, T2, or T3. Pericardial effusion is classified according to the same rules. d Separate metastatic tumor nodule(s) in the ipsilateral non-primary-tumor lobe(s) of the lung are also classified M1. b

and their main intrathoracic branches and tributaries. The point at which the pulmonary vessels become great vessels (a T4 descriptor) is the pericardium: the intrapericardial portions of these vessels are considered to be great vessels. As an example, a tumor of 5 cm in diameter, involving the ipsilateral mediastinal lymph glands and with an additional pulmonary nodule, believed to be malignant, in the contralateral lung would be described as T2N2M1.

For convenience, TNM subsets with similar survival prospects and for which treatment options would be similar are combined into stage groups (Table 9.2) and the example given above would be assigned to stage IV. Staging is done at various time points during the patient’s journey through preliminary investigations and then treatment. It is important to know when staging is done so as to compare like with like when

Staging, classiﬁcation, and prognosis 99

Table 9.2 Stage

0 IA IB IIA IIB IIIA

IIIB

IV

Stage grouping: TNM subsetsa,b TNM subset

Carcinoma in situ T1N0M0 T2N0M0 T1N1M0 T2N1M0 T3N0M0 T3N1M0 T1N2M0 T2N2M0 T3N2M0 T4N0M0 T4N1M0 T4N2M0 T1N3M0 T2N3M0 T3N3M0 T4N3M0 Any T Any N M1

a

Staging is not relevant for occult carcinoma, designated TXN0M0. Reproduced with the kind permission of Dr CF Mountain and the Editor of Chest.2 b

evaluating different treatment regimens. The initial, pretreatment, stage is the clinical/evaluative stage, or cTNM. This may integrate the information obtained from imaging and bronchoscopy as well as, for example, the histopathology from a fine needle aspiration biopsy (FNAB) of a distant metastasis. Obviously, with the addition of information obtained at surgery and the pathologic examination of the resection specimen, the postsurgical/pathologic stage known as the pTNM will be more accurate. (See comments later on ‘stage migration’.) The ‘y’ prefix is used when the patient is restaged after induction or neo-adjuvant therapy (induction therapy being a treatment modality aimed at rendering an inoperable stage tumor operable; the goal of neoadjuvant therapy is to improve the survival rate of an operable tumor). This can be used in conjunction with the ‘c’ and ‘p’ prefixes. Thus ycTNM would reflect the clinical restaging after induction or neo-adjuvant therapy and ypTNM the pathologic (i.e. postsurgical) stage after similar presurgical chemo- and/or radiotherapy. The ‘r’ prefix is used for the staging of recurrent tumors and the ‘a’ prefix for autopsy findings.4 It is important to understand the principle differences the fifth edition of the TNM Classification of

Malignant Tumors brought to the staging system for lung cancer in 1997 as many studies on induction/ neo-adjuvant therapy were designed and/or implemented before that year. The four main differences are: (1) that stages I and II were subdivided, respectively, into stages IA, IB and IIA, IIB; these reflect the increase in size of the tumor from T1 to T2 (i.e. ≤ or >3cm in diameter); (2) stage T3N0M0 was moved from stage IIIA to IIB as the five-year survival is more akin to this latter stage; (3) separate nodules within the same lobe were assigned to the T4 category; and (4) separate nodules in other, ipsilateral lobes and the contralateral lung were included in M1 disease. Many clinicians feel that such detailed staging is irrelevant for SCLC, and consider that a cruder division into ‘limited’ and ‘extensive’ disease allows clinical decisions to be made on treatment.6 There are two definitions: from the Veterans Administration Lung Study Group (VALG) and from the International Association for the Study of Lung Cancer (IASLC). In the former, limited disease (LD) is defined as tumor which is restricted to one hemithorax, often including the ipsilateral supraclavicular fossa, basically a single radiotherapy field, whilst any wider-spread disease, including distant metastases, is considered as extensive disease. In the IASLC staging system all patients without distant metastases are considered to have LD, including those with a malignant pleural effusion and all patients with contralateral mediastinal and/or supraclavicular lymph node metastases to be included in the LD category. It has been shown that the IASLC staging system is a better discriminator of survival.7 Whilst this distinction is certainly sufficient for the vast majority of sufferers with this cell type the TNM stage remains relevant for the fortunate patient with unusually localized disease (stage I essentially, possibly stage IIA) for whom surgical therapy or multimodality therapy should be considered.5,8

THE STAGING PROCESS The clinician is confronted with a bewildering array of tests which may, when used appropriately, provide information as to the extent of disease and therefore permit one to stage the patient and advise on therapy. The value and place of each test will be discussed in the

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next section. The clinician may utilize any and all such tests to construct a clinical/evaluative TNM stage (cTNM). Such tests may include surgical exploration such as mediastinoscopy and video-assisted thoracoscopy (VATS) undertaken prior to a decision to recommend treatment. It is as well to remember that as one proceeds with this information-gathering exercise, the tests become increasingly costly and more invasive. Once sufficient information has been collected as to permit a decision regarding treatment, then further tests become obtrusive and unwarranted. The difficulty for the clinician is to know where to draw the line and to decide that the evidence is sufficiently reliable as to make the case for a particular treatment. There can be no rigid protocol for staging and the clinician will decide the next step based upon the overall picture as it emerges as each step provides additional information. For most clinicians the critical point in the staging process is reached once the patient’s disease has been shown to be too extensive to permit surgical treatment. The oncologist or radiotherapist might still consider other staging tests to be important in defining the most appropriate regimen. If the patient comes through the assessment of the clinician and is still considered operable, the surgeon may wish to define the stage more precisely before making a final decision to operate. As this frequently involves a decision as to the probable extent of resection, and the use of surgical investigations such as mediastinoscopy, this step should be left to the surgeon. The issue as to which tests are considered the minimum necessary to establish cTNM has been considered by the IASLC, and is one that is regularly updated at their workshops.9,10 The American Thoracic Society and the European Respiratory Society have accepted similar recommendations.11 More recent guidelines have been published by the American College of Chest Physicians (ACCP) in 2003,12 and by the National Institute for Health and Clinical Excellence (NICE) in the UK in 2005.13 A summary of these recommendations is shown in Table 9.3. Once a decision has been made as to treatment, the cTNM assigned to that patient should not be changed in the records. As alluded to above, additional information will accumulate if the patient proceeds to thoracotomy and pulmonary resection. This will allow the pTNM to be established. This should be recorded separately, and does not replace the cTNM. The UICC4 allows and recommends that a record be made of the assessment of residual disease after treatment. This is also the recommendation in the

Manual for Staging of Cancer, produced by the American Joint Committee on Cancer Staging and End Results Reporting.15 This is most usually done after surgical resection. The designation R is used to define this. RX indicates that it is not possible to evaluate the presence of residual disease. R0 indicates that no residual disease remains, i.e. that there was a complete resection with all resection margins through normal, non-tumoral tissues. R1 indicates that microscopic residual tumor remains and R2 signifies that there is macroscopic residual tumor after what must be considered an incomplete resection. Most workers interpret the R1 status as applying to the case where the resection margins are unexpectedly positive on subsequent histologic examination of the resection specimen. Honest surgeons will also use this descriptor when tumor tissue has been cleaved off remaining structures. This classification is not part of the staging system but represents good practice. The 2005 IASLC guidelines define the requirements of complete resection.16 These require histologically proven free resection margins, complete lymph node clearance (vide infra) with no extracapsular spread in the nodes, and disease-free highest mediastinal node. We believe that at least six lymph node stations (three N1 and three N2) need to be completely resected (as opposed to sampled) to qualify as lymph node clearance, as specified in the European Society of Thoracic Surgeons (ESTS) guidelines for intraoperative staging.17 When the resection margins are free but all of these criteria are not met, or if there is carcinoma in situ at the bronchial resection margin, or if the pleural lavage cytology is positive, then the term ‘uncertain resection’ should be used. As time passes the disease may recur or progress and additional tests may be indicated to establish a retreatment or rTNM. Some would consider that our ultimate insight into the extent of disease is realized at autopsy, when a TNM can be created. However, time is the ultimate test and our understanding of disease progression is curtailed by death, preventing the development of clinically relevant disease that could be overlooked at autopsy. In summary, the first step in the evaluation of a patient with suspected lung cancer is to take a very careful history and perform a thorough physical examination. Chest radiographs and computerized tomographic (CT) scans (chest and abdomen to include the entire liver and both adrenals) are then obtained. Bronchoscopy will usually be performed at this time, especially if the tumor is centrally located. If there is a suspicion of brain metastases appropriate imaging will

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Table 9.3 Pretreatment minimal staging6,9,11,12

Step 1 Investigation Clinical history

Weight loss and performance status

Patient group All patients

Clinical examination Chest radiographs

All patients PA All patients Lateral Blood tests Hb All patients Alk phosphatase Transaminase Lactate dehydrogenase If still thought suitable for curative therapy proceed to Step II Step II Investigation Bronchoscopy

Patient group All patients with central tumors or those in whom central extension is suspected All patients if available

Confirmatory tests As appropriate As appropriate Aspiration of any effusion (considered positive if cytology malignant) As for high-risk patients in Step II

Confirmatory tests The features of proximal, extrinsic compression are unreliable and require further evaluation of the mediastinum by CT and/or mediastinal exploration Dubious findings confirmed (not necessarily histologic)

CT chest and upper abdomen (to lower pole of kidneys with iv contrast enhancement of mediastinal vessels) Liver ultrasound High risk groupa if CT of abdomen not available Brain assessment by Advisable in high risk groupa MRI (or CT if MRI not available) a High risk patients are those having non-specific features identified by Hooper et al.14 • Unexplained anaemia (Hb <11%) • Unexplained weight loss (>8 lb (3 kg) in 6 months) • Abnormal alk phosphatase, or transaminase • Where any clinical suspicion of metastatic disease exists • Patients with stage III disease If still thought suitable for curative treatment proceed to Step III Step III Investigation (a) PET-CT (b) Bone scan only if PET not available (c) Bronchoscopy if not previously undertaken (d) Thoracoscopy (video-assisted)

Patient group All patients Skeletal X-rays ± CT/MRI of bone if dubious positive result All patients If pleural effusion present and cytology negative but clinical suspicion remains, do a pleural biopsy (Continued)

102 Textbook of Lung Cancer Table 9.3 Continued

(e) Mediastinal exploration • It is recommended that this is performed pre-operatively by: • Transtracheal or transesophageal aspiration

Patients in whom CT suggests mediastinal invasion or if CT shows aspiration nodes >1.0 cm in Short axis diameter • Cervical mediastinoscopy Same • Additional evaluation of the The above groups with tumors of the left upper subaortic fossa by left anterior lobe or left main bronchus if suspicion of station mediastinotomy or VATS 5 or 6 metastases on CT or PET • This must be performed All patients – including those whose intra-operatively mediastinum has been assessed preoperatively • Palpation insufficient • Careful and extensive mediastinal dissection (‘systematic nodal dissection’) • Separate labeling as per Naruke or ATS of excised nodes for subsequent histologic examination (only N1 nodes on resection specimen) • Re-evaluation of T stage: completion of intra-operative staging of tumor and pleural space Proceed with definitive therapy, which will be surgical resection in all but the most unusual circumstances

be obtained (preferably magnetic resonance imaging (MRI) – vide infra). If the patient is a candidate for radical (i.e. ‘curative’) therapy then a positron emission tomography (PET)-CT should be obtained.13 While this staging process is being undertaken the functional evaluation of the patient can be carried out so that at the end of this process a treatment decision can be made. If the treatment decision is to give the patient induction therapy this process will need to be repeated at the term of the induction therapy so as to determine the logical next step. THE STAGING TESTS Lung cancer is dealt with nowadays by teams which comprise pulmonary physicians, surgeons, oncologists, radiotherapists, palliative care physicians, radiologists, pathologists, and numerous support staff. In the UK this is known as the multidisciplinary team (MDT). In an age of technologic progress it is often necessary to

remind ourselves of the importance of good clinical acumen. All of our elaborate scans have to be directed by clinical assessment and interpreted in the light of this. Clinical history and examination These remain the most basic and most cost-effective assessments of disease extent. The clinician, whilst enquiring as to symptoms of the primary tumor, will be looking to assess performance status and co-morbid conditions. Watching the patient come into the consultation room and careful enquiry into his/her functional status and exercise tolerance will determine the patient’s ability to undergo aggressive treatment, be it surgery, chemotherapy, or radiotherapy. Investigations may be curtailed in a very unfit patient because their results will not influence treatment choices. The performance status (Table 9.4) of every patient should be recorded at the first clinical visit. A few questions are critical to assess stage. The presence of chest wall pain is more accurate at determining

Staging, classiﬁcation, and prognosis 103

Table 9.4 ECOG performance status142 Grade

ECOG performance status

0

Fully active, able to carry on all predisease performance without restriction Restricted in physically strenuous activity but ambulatory and able to carry out work of a light or sedentary nature, e.g. light house work, office work Ambulatory and capable of all self-care but unable to carry out any work activities; up and about more than 50% of waking hours Capable of only limited self-care, confined to bed or chair more than 50% of waking hours Completely disabled; cannot carry out any self-care; totally confined to bed or chair Dead

1

2

3

4 5

chest wall invasion than a CT scan. The presence of unexplained weight loss should alert the clinician to the increased possibility of disseminated disease in such patients. A patient may well dismiss weight loss as attributable to changes in diet and a deliberate attempt at weight reduction. Further enquiry may show that repeated previous attempts at weight reduction have failed without the assistance of disseminated malignancy! The patient coming to see a chest specialist will not volunteer the recent onset of bone pain, assuming it to be degenerative or traumatic in nature, and may assume that hoarseness is due to the trauma of coughing. Similarly, patients and their relatives may rationalize the change in personality as due to anxiety after hearing the diagnosis and dismiss neurologic symptoms as due to minor nerve damage. A careful examination should focus upon any questions raised in the history and also routinely examine for cervical lymphadenopathy and hepatomegaly. One’s ability to detect enlarged neck nodes improves with practice and this important examination should not be designated to the most junior member of the team. Examination of the supra-clavicular fossa with ultrasound (US)-guided FNAB is becoming increasingly popular and does detect a number of otherwise unsuspected lymph node metastases, which are very important as they are an N3 determinant (stage IIIB). When reading the literature on routine US screening of the supra-clavicular fossa it is important to determine the prevalence of nodal disease, which will be related to

the inclusion criteria for the study (patients with ‘operable’ NSCLC vs all patients with suspected or proven NSCLC vs patients with suspected N2 disease) as this has an obvious impact on the incidence of N3 disease detected by this investigation. Thus in one study of ‘operable’ patients with NSCLC this technique proved N3 disease by virtue of supra-clavicular lymph node metastases in 8% of patients, but this led to upstaging of only 4%.19 In a study of patients with lung cancer at any stage, 31% were found to have supra-clavicular lymph node metastases in non-palpable nodes.20 This was the same frequency as probable or proven adrenal metastases and the supra-clavicular lymph node metastases were often associated with mediastinal lymphadenopathy and/or other distant metastatic disease. This study also showed that US was superior to CT in detecting non-palpable supra-clavicular lymph node metastases. Finally, the yield was again very low in otherwise apparently operable patients with NSCLC. In one study of patients with NSCLC and probable stage N2 disease, 46% of patients were found to have supra-clavicular lymph node metastases, and this obviated the need for other staging procedures in 42%.21 These results have two implications. First it means that US-guided FNAB of supra-clavicular lymph nodes will obviate the need for more invasive staging procedures in a significant number of patients, sparing them the risks of the procedure and making considerable cost savings for the health-care economy. Second, it will upstage a significant number of patients, and this can have considerable therapeutic consequences as in many cases this will mean a shift from so-called curative treatment modalities to a more palliative approach. However, the yield and benefit are greatest in patients who are already suspected of having at least stage IIIA disease, and the yield in patients with stage I and II disease is much more limited, making its routine application for this subset of patients much more debatable. This finding was confirmed in another study in which only 3/117 patients were upstaged by supra-clavicular US-guided biopsy of non-palpable lymph nodes.22 Chest radiography This is usually the starting point in further evaluation. Whilst it usually provides clues as to the diagnosis, it also gives valuable staging information as to tumor size and possible local invasion.23 It is as well to check the radiograph for rib erosion, elevation of the hemidiaphragm, the presence of other lung nodules, or evidence of an effusion (Figure 9.1). The presence of such features may allow one to cut short the process of

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the surgeon will wish to examine the airway with respiration suspended under general anesthesia, often using the rigid bronchoscope with its wider field of view and facility for larger biopsies. Bronchoscopy also allows the clinician to rule out other small endobronchial tumors and demonstrates anatomic variants of bronchial anatomy to the surgeon.

Figure 9.1 The chest radiograph of a patient with a mass in the right upper lobe (arrow). The film also shows gross widening of the superior mediastinum (arrow head), strongly suggestive of mediastinal nodal disease, but there is also a right pleural effusion. Aspiration cytology of the effusion gave the diagnosis of adenocarcinoma, allowed staging of the disease as T4 (stage IIIB), and also showed the patient to be inoperable.

assessment by establishing the diagnosis and staging the patient with a single investigation, such as pleural aspiration cytology. The posteroanterior and lateral films can also be useful for tumor localization in relation to the fissures. Hematologic parameters Parameters such as anemia, disturbance of liver enzymes, or elevation of serum alkaline phosphatase are reliable indicators, suggesting a greater probability of distant disease.24 Such tests are inexpensive and widely available, and should be a routine part of the staging process. Bronchoscopy For the patient who remains operable at this point a wide vista of additional tests may be appropriate. The diagnosis may be established by sputum cytology, an underutilized investigation, but for all patients except those with extensive disease, bronchoscopy will be undertaken. This provides an opportunity for more accurate determination of cell type by histologic examination and allows one to assess the proximal extent of the disease within the tracheobronchial tree. The fiberoptic bronchoscope is an excellent screening tool for the respiratory physician, but in borderline cases

Computerized tomography CT has greatly aided the staging of lung cancer and the proliferation of CT scanning facilities attests to the enormous value of this investigation. However, much depends upon technical aspects of the scanner, the protocol used for the study, and the experience of the radiologist.25 CT scans of the chest provide an enormous amount of three-dimensional information as to disease extent. One can analyze the individual components of the scan, assessing the accuracy with which CT can detect mediastinal gland involvement, mediastinal invasion, chest wall invasion, the presence of additional pulmonary nodules, or deposits in the abdominal organs or brain. However, in reality the value of the information provided by CT scanning is far greater than the sum of its component parts. The three-dimensional construct helps the surgeon anticipate the possible extent of resection, the technical problems that may be encountered, and the areas to inspect for possible tumor extension. The surgeon can use such information in evaluating the patient’s fitness for such extended surgery, to guide intraoperative assessment, and to plan the operative strategy to deal with likely areas of extension or concern. It does not matter to the surgeon that such areas of concern may prove to be fallacious, it is better to be prepared, but for the clinician the lack of specificity must be an ever-present concern in evaluating the true extent of disease. One would not want to deny the patient potentially curative surgery on the basis of a radiographic feature that lacks accuracy. Confirmatory tests are often necessary, particularly if the decision hinges upon a single, adverse CT feature. The significance of additional pulmonary nodules will depend upon geographic factors such as the local prevalence of benign granulomatous disease. In one study, two-thirds of such nodules were shown to be definitely benign, and only 11% were definitely malignant.26 Mediastinal lymph nodes can be seen more easily on CT than with conventional radiology.27 As the size of such nodes increases, so does the probability that they contain metastases. However, there is no size criterion below which deposits are excluded with certainty, nor above which deposits are certain to be present (Figure 9.2).

Staging, classiﬁcation, and prognosis 105

Figure 9.2 A CT scan of the chest with contrast enhancement of the mediastinal vessels. An enlarged node is visible in the right paratracheal area (arrow). Although this node was larger than 1 cm, it was shown at mediastinoscopy to be benign, and this was confirmed at subsequent thoracotomy.

Figure 9.3 A CT scan of a patient with a left upper lobe tumor. The CT shows unequivocal evidence of irresectable involvement of the mediastinum with tumor encircling the main pulmonary artery to its origin. A left anterior mediastinotomy would be unnecessary unless tissue diagnosis was required.

As one increases the size limit permitted for normality, those nodes deemed ‘abnormal’ are more likely to contain metastases, and the evaluation gains greater specificity, but at the cost of declining sensitivity. If one applies a lower cut-off the reverse applies, sensitivity rises at the expense of falling specificity, and one is more likely to designate nodes as ‘abnormal’ when they do not contain metastases.28 This is the dilemma for the radiologist. The commonest compromise is to report nodes as abnormal if their short-axis diameter is greater than 1.0 cm.29 The accuracy of this assessment depends upon many factors: the speed of the scanner, the use of contrast to enhance the mediastinal vessels, and the rigor with which lymph node deposits are sought at thoracotomy. The reported sensitivity and specificity fall from 70–80% to 60% when the CT assessment is subjected to detailed intrathoracic staging.30–32 Abnormal nodes, larger than this, should be examined by mediastinal exploration to gain histologic confirmation of their involvement. Such enlarged nodes within the superior mediastinum are accessible to cervical mediastinoscopy and anterior mediastinotomy (see later). Enlarged nodes beyond the reach of these techniques can be accessible to video-assisted thoracoscopy (VATS),33 but such nodes have less impact on the results of surgical treatment and their accurate designation can usually be left until thoracotomy. If the CT scan of the chest shows the mediastinal nodes are within this size limit the surgeon may proceed to thoracotomy without mediastinal exploration.34 However, there are four classic risk factors for false negative mediastinal imaging studies (including position emission tomography (PET) scanning, which will be

discussed below). These are: large tumors, central tumors, PET-positive hilar nodes, and cell type of adenocarcinoma or large cell poorly differentiated carcinoma.35 This should be taken into account when deciding whether invasive mediastinal staging is indicated. Also, many surgeons will be more cautious (i.e. more extensive in their preoperative staging) when faced with a higher risk resection (right pneumonectomy, for example) or a high-risk patient, or both together. Mediastinal invasion may be suggested on CT, but this assessment is unreliable36 unless there is gross involvement (Figure 9.3). More frequently the CT scan of the chest will show that the tumor, and the associated atelectasis or consolidation, is contiguous with the mediastinal outline (Figure 9.4). If CT does not demonstrate a fat line separating these two opacities the radiologist will warn that invasion may be present.37 This judgement carries a sensitivity and specificity of around 60%,38 but is imperfect and dependent upon the experience of the radiologist. Such a worry can often be resolved by mediastinoscopy (Figure 9.5), with the addition of mediastinotomy in appropriate cases. A suggestion of mediastinal invasion beyond the reach of these techniques can be inspected using VATS, but is usually deferred until thoracotomy when a more determined assessment of resectability can be made without the danger of massive bleeding. The CT evaluation of chest wall invasion is similarly imperfect unless rib erosion or extension outside the chest wall can be demonstrated.39 Fortunately, such invasion does not preclude successful resection with good survival results.40,41 Most clinicians when requesting a CT scan will ask for the chest study to extend into the abdomen to the

106 Textbook of Lung Cancer Figure 9.4 A chest radiograph (a) and CT scan (b) of a patient with a tumor in the right middle lobe. This was initially deemed inoperable by another clinician based on his interpretation of the CT scan. The appearances are not unequivocal and at thoracotomy resection of a T2N0 tumor was possible by bilobectomy. The chest radiograph (c) was taken 3 years later and the patient is still well and diseasefree 12 years later.

Figure 9.5 The CT scan of a patient with a tumor in the right upper lobe encroaching upon the mediastinum and the right main bronchus. This was evaluated by mediastinoscopy and found to be resectable. The patient underwent right upper lobectomy and sleeve resection for a T2N1 tumor.

Figure 9.6 The CT of the abdomen suggested a liver metastasis. The appearances were not clarified by ultrasound and a needle biopsy showed a benign hemangioma.

lower pole of the kidneys in a search for distant metastases in the liver, abdominal nodes, adrenals, and kidneys. Whilst this is a useful addition to the CT protocol, an isolated abnormality should not be taken as proof unless there is confirmatory evidence that such an abnormality is metastatic (Figure 9.6).42 This may require CT-guided needle biopsy (Figure 9.7). We have

found this to be a useful role for PET, if this is available (see later). The addition of CT of the brain is debated. Undoubtedly the number of unsuspected metastases discovered is small, around 5%,12,43 but as this has a profound effect on the advisability of thoracotomy we routinely undertake CT of the brain, chest, and abdomen prior to surgery.44 If there is any suspicion of

Staging, classiﬁcation, and prognosis 107

Figure 9.7 A CT-guided needle biopsy of an indeterminate mass in the right adrenal gland. It showed the presence of an adenoma.

brain metastases, and indeed for screening purposes, MRI should always be the preferred brain imaging modality unless local availability is an issue.45,46 Scintigraphic scans These are largely obsolete, with the possible exception of bone scintigraphy.47 This has retained a place in staging if and only if PET is not available. Most clinicians use bone scans selectively in ‘high-risk’ individuals in whom distant metastases have been suggested clinically by symptoms, or the presence of non-specific features such as weight loss or disturbed blood parameters.48,49 As false-positive bone scans can occur with trauma and degenerative conditions it is as well to follow up any abnormality with skeletal radiology, and in doubtful cases a local CT or MRI of the area.50 However, if a whole body PET scan is obtained then the bone scan is redundant. PET has both higher sensitivity and higher specificity than scintigraphic bone scans.51–53 However, despite this higher accuracy confirmatory studies should be performed if there is any doubt about the diagnosis of metastatic disease.12 Abdominal ultrasound This is widely available and, in experienced hands, is as good as CT at detecting metastases in the liver54 or adrenals.55 If CT is not available, US should be performed in high-risk cases. US is helpful to obtain additional information to characterize any abdominal abnormality on CT, and may obviate the need for needle biopsy. It is also a useful guiding technique for the biopsy, if required.

Mediastinal exploration This is a fundamental tool to select patients for surgery because of the strong negative prognostic implication of N2 and N3 disease. The ESTS has recently published guidelines on both the pre-operative and the intra-operative lymph node staging.17,35 If it is felt that the patient would be a candidate for induction (also called neo-adjuvant) therapy, then it may be desirable to avoid surgical staging of the mediastinum so that the most definitive procedure can be carried out in an unoperated and unscarred mediastinum at the end of the induction therapy (see section below on restaging of the mediastinum after induction therapy). It can also be desirable to avoid surgical staging in more frail patients. Unfortunately, the reliability (the combined sensitivity and specificity) of all techniques increases with invasiveness. The true gold standard of mediastinal staging is the systematic nodal dissection done at the time of thoracotomy. Mediastinoscopy has a false-negative rate of less than 10%,56 whereas all endoscopic techniques with FNAB have a false-negative rate of around 15% in the best of hands. So the decision as to how to proceed will depend on the clinical indices of suspicion for mediastinal lymph node involvement as well as the patient and the planned resection, as it is clearly desirable to avoid the discovery of false-negative staging at thoracotomy in a high-risk situation. So in most centers mediastinoscopy is now used selectively to evaluate the mediastinum when CT has suggested the presence of enlarged mediastinal nodes or mediastinal invasion,57 if there are PET-positive nodes in the mediastinum, or if there are other clinical indices leading to heightened suspicion of mediastinal lymph node involvement. Cervical mediastinoscopy58 is undertaken under general anesthesia through a short cervical incision. It allows inspection and biopsy of lymph nodes in the paratracheal region to both sides of the trachea, in the pretracheal area, and below the carina, excluding gross, often irresectable, nodal metastases. When the nodes are of a normal size and metastases are small and intranodal there is obviously a risk of sampling error, and this is the most common cause of false-negative mediastinoscopy. The one area where more overt mediastinal nodal deposits can be missed is classically the inferior part of station 7 (the subcarinal nodes) as well as its most posterior aspect. This risk can be minimized by dissecting station 7 off both left and right main bronchi, as well as off the pericardium posteriorly prior to taking biopsies. There are several reports of falsenegative rates of well over 10%. We feel that using a

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video mediastinoscope, with its greatly enhanced vision, this is unacceptable and, if this is the case, the surgeon should consider taking more care to identify all possible nodes, to dissect them out more so that larger biopsies can be taken safely, and to prepare the subcarinal fossa as described above so that it can be extensively biopsied. When the tumor is a left-sided tumor it is the practice of the authors to do this part of the mediastinoscopy quite aggressively because it then becomes part of the systematic nodal dissection. Likewise, as it is extremely difficult to reach L4 and L2 effectively through a left thoracotomy, it is the practice of the authors to resect as many nodes as possible at mediastinoscopy, again with the view that mediastinoscopy, if negative, will then become a seamless part of the operative management of the tumor, fulfilling the philosophy of intraoperative staging as described in the ESTS guidelines.17 Two more radical methods of mediastinal staging have been described. These are VAMLA (video-assisted mediastinoscopic lymphadenectomy) and TEMLA (transcervical extended mediastinal lymphadenectomy).59–61 As the names imply, both techniques aim to perform a radical mediastinal lymphadenectomy removing all the para-tracheal nodes as well as emptying out in a radical manner the subcarinal fossa (and therefore more than just station 7). TEMLA also aims to remove stations 5, 6, and 8. In experienced hands these techniques can be performed safely with entirely acceptable morbidity. However, at the moment experience is limited and they are only performed in a few centers. Furthermore their exact place in mediastinal staging remains to be established. First, do we truly want a perfect method to stage the mediastinum? Patients with true minimal N2 disease (single-station, intracapsular involvement) have a 25–40% five-year survival with surgery alone. It is uncertain whether it is in these patients’ best interest to be denied surgery because they are found to have N2 disease. Second, at the end of this chapter we shall explore the issue of restaging the mediastinum after induction chemotherapy. It is when the N2 disease has been eradicated that there is an indication for surgery. This would be impossible after VAMLA or TEMLA, making the decision whether to proceed with surgery more difficult because all that would be left would be to assess the decrease in the maximal standardized uptake value (SUV max) of the primary tumor as a measure of the response to induction chemotherapy. The major advantage for such techniques at present would appear to be in allowing the mediastinal component of systematic nodal dissection (see later) to be

performed prior to surgery when video-assisted resection is planned. Mediastinoscopy can also be very useful to assess direct mediastinal invasion by right upper lobe tumors, so in some cases it can also be useful to assess T stage and thus resectability. When wishing to inspect the area around the aortic arch and subaortic fossa, as in patients with tumors arising in the left upper lobe or reaching the left main bronchus, cervical mediastinoscopy should be supplemented by left anterior mediastinotomy.58 This allows digital examination and, if necessary, cautious biopsy of disease in this area (Figure 9.8). It is applied selectively depending upon the CT appearances in this area of the mediastinum.62 Some surgeons prefer to use VATS to biopsy stations 5 and 6. Such techniques do not exclude more subtle mediastinal disease but, with experience, ensure that complete resection is possible in 95% of negative cases.63,64 The surgeon will often be encouraged to proceed with thoracotomy and resection when other, less accurate techniques such as CT have raised doubts. When the lung cancer is in the left upper lobe and the CT shows only small-volume nodes, completely surrounded by fat, in the para- or subaortic area on CT, some surgeons do not routinely explore this area preoperatively because the five-year survival in patients with this pattern of nodal disease may be equivalent to that of patients with N1 (i.e. stage II) disease, and not that of patients with N2 (i.e. stage IIIA disease).65,66 Mediastinal needle biopsy This can be undertaken through the bronchoscope.67 Suitable target nodes should be identified in the main

Figure 9.8 This patient has a tumor in the left upper lobe and the surgeon is undertaking evaluation by cervical mediastinoscopy and left anterior mediastinotomy. After all biopsies have been taken, bi-digital palpation of the subaortic fossa will exclude invasion or gross mediastinal gland enlargement in this critical area.

Staging, classiﬁcation, and prognosis 109

carina or the paratracheal area, usually on CT. This technique may obtain tissue diagnosis and confirm irresectability, but there is a small risk of false-positive samples.68,69 It cannot be considered to be a reliable alternative to staging the mediastinum by surgical exploration prior to thoracotomy, even with US-guided biopsies. Overall, bronchoscopic FNAB techniques have a false-negative rate of around 15%, so the main value of these techniques is when this minimally invasive technique proves mediastinal lymph node involvement. Transesophageal fine needle aspiration (with ultrasound guidence) EUS-FNA has been used to assess the presence of mediastinal node enlargement, but is limited by the same size criteria as CT.70 The transesophageal route is attractive as a conduit to examine the mediastinum below the carina, beyond the reach of the mediastinoscope, as well as the left para-tracheal area, checking areas where CT has suggested mediastinal lymph node involvement or tumor invasion. The results have proven unreliable,71 being of a similar order of magnitude as with trans-tracheal biopsies. The same caveats therefore apply to this technique, even with US guidance. However, it has been shown that EUS-FNA can be used to improve the yield of mediastinoscopy.69 In this study there were 36/100 patients who were ultimately proven to have N2/N3 disease. These were located within reach of EUS-FNA in 29 patients, and were positive at EUSFNA in 22. Mediastinoscopy detected N2 (17%) or N3 (2%) lymph node metastases in 19 of the 100 patients. These were located within reach of mediastinoscopy in 29 patients and were confirmed in 19 of these patients. Lymph node metastases were confirmed in 31 (86%) of 36 patients by either EUS-FNA or mediastinoscopy. The five lymph node metastases that were missed by both techniques were located at station 4L in one patient, 5 in one patient, 7 in two patients, and 8 in one patient. This study also showed that T4 status can be correctly assessed by this technique in a number of cases. Similar results with this combined technique have been reported by others.72 Positron emission tomography PET using the 18F-labeled glucose analog fluoro-2-deoxy-D-glucose (FDG-PET) has emerged as an exciting addition to the staging tests. It is expensive, and in many areas is still not widely available, and we are still assessing its cost-effectiveness. It provides an alternative, metabolic search for malignant disease that is independent of the anatomic features of the deposits and is

thus a useful tool to detect and characterize the primary tumor as well as loco-regional and distant metastases.73 It can characterize the lung lesion reliably in many cases,74 failing only to detect very small deposits and more indolent tumors such as broncho-alveolar carcinoma.75 False-positive cases can occur with chronic inflammatory conditions, most notably tuberculosis and histoplasmosis. PET may thus have a role in diagnosis and its place relative to bronchoscopy or needle aspiration is under discussion.76 PET is reliable for lesions that are over 8–10 mm in diameter, and should probably not be performed for smaller lesions.12 Interest, however, has focused on the possibility that PET could aid the non-invasive search for metastatic disease in the mediastinum and at distant sites.77 Initially it was said that PET is more accurate in the detection of mediastinal nodal disease than CT and even mediastinal exploration, with a reported sensitivity of 80–100% and specificity of 70–100%.78 However, the images produced by FDG-PET scanners are indistinct and lack anatomic precision (Figure 9.9). It is difficult to accurately define the margins of hilum and mediastinum. In many centers this problem has been addressed by concomitant PET and CT scanning in a dedicated PET-CT scanner. Two studies have shown the superiority of integrated PET-CT as compared to the combination of a PET study and a CT with correlation of the images by the examining physician.79,80 This superiority was found to be significant for the determination of T stage, N stage, and M stage. A final caveat regarding PET is that one study has shown it to be significantly less reliable in smokers (or recent quitters) than in non-smokers.81 The maximal SUV was also higher in never-smokers, both in the primary tumor and in mediastinal metastases. This could be due to the fact that the background FDG uptake is higher in smokers than in never-smokers. Most centers having access to PET continue to rely upon CT and confirm positive PET findings by mediastinal exploration, thus adding to the expense of staging.82 There is also the philosophical problem as to whether one wishes to detect all mediastinal nodal deposits. There are many reports of five-year survival of 20–30% after complete resection in the presence of truly minimal N2 disease.64,83–85 Mediastinal exploration will miss such subtle N2 disease, perhaps to the patient’s benefit, encouraging one to proceed with surgery with complete resection in 85% of cases.64 It is unknown to what extent detection of this minimal N2 burden and induction chemotherapy would alter the natural history of this entire very small subset of patients (because induction therapy does not eradicate

110 Textbook of Lung Cancer Figure 9.9 The chest radiograph (a) of a patient who presented with a tumor in the left lower lobe; there is an additional lesion at the right apex (arrow). The CT scan (b) did not suggest this additional lesion was a tumor. An FDG-PET study (c) showed high uptake in both lesions, and the rightsided lesion was confirmed histologically to be malignant.

N2 disease in the majority of patients with more bulky N2 disease). Furthermore, we do not know if the results of induction chemotherapy would be better, worse, or the same as adjuvant chemotherapy, which would now be offered to these patients unless contraindicated. PET will detect otherwise unsuspected distant metastases in 11–29% of patients otherwise thought suitable for thoracotomy.86–88 However, the specificity of this evaluation is not 100%. With regard to distant staging, the initial enthusiasm for PET needs to be tempered. A recent study with much larger numbers (350 patients) demonstrated solitary extrathoracic lesions in 72 patients (21%). A diagnosis was obtained in 69: 37 were true metastases, 32 were not. These 32 lesions proved to be unrelated malignancies in 6 and benign tumors or inflammatory lesions in 26.89 Similarly, in the study by Reed et al otherwise unsuspected metastatic disease was identified in 15/287 (5.2%), as well as three second primary tumors. However, PET also identified 19 potential areas of M1 disease that were proven not to be metastases (6.6%). Thus the sensitivity of PET for M1 disease was 83%, the specificity was 90%, the negative predictive value was 99%, and the positive predictive

value was 36%.90 This underscores the value of the recommendation in the current ACCP12 and NICE13 guidelines for histologic verification of apparent solitary metastases detected by PET. Similarly our experience with PET as a staging tool for the mediastinum has grown and some of the initial enthusiasm has been tempered by this experience. There have been many recent studies and all essentially show similar results to the three published reports.90–92 These studies included between 202 and 400 patients. The sensitivity of PET ranged from 64 to 71%, the specificity from 77 to 84%, the positive predictive value from 44 to 56%, and the negative predictive value from 87 to 91% (Table 9.5). An editorial by Kernstine explains why these values are the best one can expect with the current technology.93 What these results mean is that, if one relies exclusively on PET to rule out N2/ N3 disease, between 9 and 13% of patients will be found at thoracotomy to have unexpected N2 disease which might have precluded surgery. Putting together what we know from the CT era and this knowledge it seems reasonable to proceed with thoracotomy for small, peripheral tumors (unless known to be an adenocarcinoma or

Staging, classiﬁcation, and prognosis 111

Table 9.5 Accuracy of PET-CT for mediastinal staging Reference

Number of patients

Sensitivity (%)

Specificity (%)

Positive predictive value (%)

Negative predictive value (%)

Reed et al90 Gonzalez-Stawinski et al91 Cerfolio et al92

303 202

61 64

84 77

56 45

87 88

400

71

67

44

91

poorly differentiated large cell carcinoma) on the basis of the PET scan alone, provided that the surgeon is prepared to resect unexpected minimal N2 disease if found, on the basis that surgery alone offers a 20–35% chance of cure in this situation.35 This might be improved with adjuvant chemotherapy if the patient is fit for this treatment modality. Otherwise, invasive staging of the mediastinum should be carried out. This does not make PET useless. First, in the apparent stage I (and possibly II) patients with peripheral lesions it can allow lung resection to be carried out without surgical staging of the mediastinum. Second, because it is precisely the patients with the highest risk of unsuspected mediastinal disease who are also at highest risk of distant metastatic disease that PET has the highest chance of detecting otherwise occult stage IV disease. Integrated PET-CT has been shown to be more accurate than PET alone with correlation to a previously performed CT;79,80 however not to a degree that fundamentally changes this discussion about the indications for surgical staging of the mediastinum. Despite all our improvements in non-invasive staging, invasive staging remains the closest we have to a prethoracotomy gold standard for the detection of N2 disease. The risk factors for unsuspected N2 disease that we knew from the CT era of staging are still pertinent in the PET age. They are tumor size, location, and histology and PET-positive hilar nodes.35 Large tumors, central tumors and adenocarcinoma/poorly differentiated large cell carcinomas present the greatest risk of false-negative non-invasive staging. The true gold standard for the precise diagnosis and assessment of N2 disease remains the intra-operative systematic nodal dissection.17 This is not only a staging tool but could also have a beneficial effect on outcome.94–97 Magnetic resonance imaging MRI is little or no more accurate than CT in routine staging. Some authorities consider that the ability to visualize in planes other than axial gives MRI an advantage

Figure 9.10 An MRI scan of a patient with a right-sided Pancoast tumor. The scan gives coronal reconstruction of this difficult area, but also suggested nodes at the main carina, which were confirmed to contain metastatic disease at mediastinoscopy.

in difficult areas such as the lung apex and lower mediastinum.98 Most would recommend MRI when evaluating Pancoast tumor (Figure 9.10).99 With modern, fast, multislice CT scanners and the software to do multiplanar reconstructions many of the advantages of MRI have been obviated. If appropriately thin cuts are obtained, modern CT scanners have higher spatial resolution than MRI. However, MRI remains of value as a problem-solving tool looking at the central nervous system. MRI is more accurate than CT at detecting and characterizing brain lesions.45,46,100 If there is a clinical suspicion of brain metastases then MRI should be obtained unless there are local availability issues. We would also recommend its use if CT of the brain shows an abnormality (to rule out multifocal disease) or when clinical suspicion remains after a negative CT. The routine use of MRI as a screening tool for asymptomatic brain metastases has not been shown to be of value. Similarly, if the CT raises doubts as to tumor extension around the spine and into the spinal canal, MRI will give clearer definition and valuable information. Whenever a neurosurgical opinion is to be sought, MRI should be obtained beforehand.

112 Textbook of Lung Cancer

The tests described above should allow one to determine cTNM and, in appropriate cases, recommend thoracotomy. For the surgeon, however, the staging process does not end there. We have come to appreciate that a detailed re-evaluation at thoracotomy is a valuable step prior to proceeding with resection. Intrathoracic staging will evaluate areas of concern remaining after CT and subsequent mediastinal evaluation, search for additional pulmonary nodules and pleural deposits not seen on CT,101 and permit a thorough evaluation of nodal extent by systematic nodal dissection.102 There is debate as to the value of pleural lavage cytology as a routine step immediately after opening the chest. Kondo and his colleagues found positive pleural cytology in 9% of cases and showed it to be a strong indicator of poor prognosis.103 Other workers have confirmed the incidence of positive cytology but did not find a statistically significant influence on prognosis after resection.104 We have reviewed our experience with pleural lavage cytology. We found malignant cells in the lavage in 4.5% of the 292 patients studied. Positive pleural lavage had a statistically highly significant and independent impact on survival: patients with positive pleural lavage had a median survival of only 13 months, as compared to 49 months for those with a negative lavage.105 Despite rigorous preoperative staging with CT and, where appropriate, mediastinal exploration, cTNM has been shown to be inaccurate in over half of the patients coming to thoracotomy.106 Whilst occasionally cTNM will overestimate the extent of disease, in most cases the disease will be shown to be more extensive. As yet we do not know precisely how the integration of newer (a)

STEP 1

(b)

tools such as PET-CT will improve this. It is clearly important that the surgeon obtains such valuable insight into the extent of disease before making a decision whether to proceed with resection, and when judging the extent of pulmonary resection necessary to achieve complete resection. Systematic nodal dissection (SND) begins with the excision of all mediastinal fat and the lymph nodes contained therein (Figure 9.11). It is recommended that the nodes be labeled in accordance with an internationally recognized chart such as that proposed by Naruke (Figure 9.12)107 or that of Mountain and Dressler (Figure 9.13).3 It is our routine to slice these nodes at the operating table and examine the internal architecture before deciding whether rapid histologic confirmation is necessary by frozen section analysis. If resection is deemed possible we proceed to examine the N1 nodes similarly, in a centrifugal fashion, until the extent of resection has been determined. The only nodes remaining in the resection specimen can be assumed to be N1. In such a way the surgeon will ensure complete resection with the minimum resection of lung parenchyma. We have shown that SND will disclose N2 disease in 18% of patients coming to thoracotomy without histologic evidence preoperatively, and only 60% of patients will be shown to be node negative.108 This study confirmed that SND could not be omitted on the basis of cell type, tumor size, tumor origin, lobe of origin, or by preoperative mediastinal exploration. As ‘skip’ lesions to the mediastinal nodes without hilar node involvement were found in 6% of cases, the assessment of the mediastinum is important irrespective of the findings in STEP 2

Figure 9.11 An operative specimen showing fat and lymph node stations removed during the first step in SND (a). These can be correlated with the Naruke chart to show that a complete circumnavigation of the right side of the mediastinum has been accomplished. Step 2 of the nodal dissection (b) removes the nodes from the fissure and the hila of the individual lobes.

Staging, classiﬁcation, and prognosis 113

1 2

1

4

5 10

10

7

13 12 14

2 3 6

10

14

2

3

2 4

1

10

10 10

10

10

11

11

12 11

8

14 13

12

8

13 14 14

14 13 12 13

13 14

13 8 13

13

14 14 9

1 3p

8

9

2 3 4

3a

9

1 Superior mediastinal or highest mediastinal 2 Paratracheal 3 Pretracheal 1 3a anterior mediastinal 3p retrotracheal or 2 3a 3 posterior mediastinal 6 4 Tracheobronchial 5 4 5 Subaoratic or Botallo’s 6 Paraaortic (ascending aorta) 7 Subcarinal 8 8 Paraesophageal (below carina) 9 Pulmonary ligament 9 10 Hilar 11 Interlobar 12 Lobar … upper lobe middle lobe and lower lobe 13 Segmental 14 Subsegmental

Figure 9.12 The nodal chart devised by Naruke. The lymph node stations are numbered: 1–9 indicate mediastinal nodal stations. (Reproduced with permission of Dr T Naruke and Mosby Inc from J Thorac Cardiovasc Surg 1978; 76: 832–9.107)

the hilum. If mediastinal node deposits are discovered at thoracotomy and yet complete resection has been confirmed to be feasible, the surgeon must decide whether to proceed with resection, balancing the reduced prospects of survival after complete resection and the added morbidity and mortality of pulmonary resection. The surgeon will be aware that the patient has already necessarily incurred the morbidity and mortality of thoracotomy (annual returns, The Society of Cardiothoracic Surgeons of Great Britain and Ireland), and will base the decision to resect upon the patient’s fitness, the extent of resection necessary, the cell type, and the number and position of positive nodes. Complete resection will be deemed appropriate in 85% of cases, although the perioperative mortality is higher and the five-year survival reduced to around 20–30%.64,83–85

Subsequent histologic examination of lymph node stations removed at surgery will show metastases that the surgeon had not appreciated in up to 9% of cases.109 The pathologist will also study the specimen and attached lymph nodes, looking for the presence of pleural invasion and satellite lesions that may have eluded the surgeon. Some authors have suggested that the use of monoclonal antibody stains will detect nodal deposits not seen with conventional stains in up to 6% of lymph nodes in 22% of patients.110 Others have suggested that this is the result of taking additional slices of the nodes and that the majority of such micrometastases will be found with conventional stains by more thorough histologic examination.111 To establish the pTNM the clinician will thus have to scrutinize the operative findings and study the detailed pathology report. The accuracy of pTNM will depend heavily on the detailed nature of such reports.

RESTAGING AFTER INDUCTION CHEMOTHERAPY A full discussion of the place of induction chemotherapy in the management of NSCLC is outside the remit of this chapter. However, if multimodality therapy is considered, restaging of the patient prior to surgery is of paramount importance. Recently there have been studies that have challenged the role of surgery in all but true minimal N2 disease (i.e. intracapsular, single node N2 disease found at the time of thoracotomy), showing apparently similar results with radical radiotherapy after induction chemotherapy.112–114 However, in one of these studies114 there was a significantly improved progression-free survival with surgery and a trend towards increased overall survival, and the authors concluded that surgery can be considered in fit patients, especially if a pneumonectomy will not be required. In another,112 the number of complete responses (only 4% overall) was far less than usually found and the pneumonectomy rate (50%) was unusually high, so it does seem fair to consider the results of the experience to date as inconclusive. The authors of this European trial112 themselves point out that we do not know what the outcome would be in the patients who are now considered to be the appropriate candidates for surgery, i.e. those who have been downstaged from N2 to N1 or N0. It is interesting to note that in this same study the locoregional recurrence rate was much lower in the surgery arm (55% vs 32% in the radiotherapy arm). Finally, RTOG 89-01 was closed prematurely to give priority to another trial, which will

114 Textbook of Lung Cancer Figure 9.13 The nodal chart established by the American Joint Committee on Cancer (AJCC) and the Union Internationale Contre le Cancer (UICC) in 1997.3 (See color plate section, page xv)

weaken the conclusions that can be drawn from this trial.113 With induction chemotherapy, typically 30–50% of patients will have the N2 nodes cleared of cancer by the induction therapy. It is interesting to note that, when there was sequential induction therapy comprising chemotherapy followed by chemoradiation therapy, and when PET was performed at the outset, after the chemotherapy and at the end of the induction process it was the postchemotherapy PET (and not the PET post-total induction therapy) that was the better predictor of survival.115 If the N2 nodes have been cleared of cancer, the fiveyear survival ranges from 29 to 44%,35,116,117 and if a pathologic complete response is observed the five-year survival is estimated to be 54% (median survival not reached).118 If, on the other hand, this is not the case then the five-year survival is 7–24%, usually below the 10–15% range in most studies. This is why it is considered essential to restage the mediastinum after induction therapy to avoid futile and potentially dangerous thoracotomies and resections if there is persistent N2 disease. Unfortunately there is no perfect tool to restage the mediastinum.35

Repeat mediastinoscopy has been used to restage the mediastinum. The best results have been published (and recently updated) by the Antwerp group.119 Over 10 years they had 32 patients who underwent repeat mediastinoscopy after induction therapy. They were able to perform the procedure in all patients and had only five false-negative repeat mediastinoscopies, yielding a sensitivity of 71%, a specificity of 100% and an accuracy of 84%. De Leyn et al reported the Leuven experience of 30 prospectively studied patients and, in their hands, there were only five positive repeat mediastinoscopies. In 18 cases the node which had been positive at the first mediastinoscopy could not be adequately assessed because of extensive scarring and fibrosis. All patients underwent thoracotomy and the systematic nodal dissection revealed persistent N2 disease in 17. Therefore the sensitivity of repeat mediastinoscopy was 29%, its specificity was 100%, and its accuracy only 60%.120 A Dutch group reported their experience with repeat mediastinoscopy in 15 patients. In 6 patients the procedure was considered to be inadequate; there were 9 adequate procedures – 2 were true positives and 2 were false negatives.121 The conclusion must be that in the real world repeat mediastinoscopy

Staging, classiﬁcation, and prognosis 115

is a challenging operation with insufficiently robust results to recommend its routine use for restaging of the mediastinum after induction therapy. CT scanning is even more inaccurate for restaging than it is for primary staging.35 PET, when used for restaging the mediastinum after induction therapy, is less accurate than when used for primary staging, with a sensitivity of 50–60% and a specificity of 85–90%.35 Fused PET-CT is better that PET alone in this situation and in one study (with by far the best results) the sensitivity was 77%, the specificity was 92%, and the accuracy was 83%.120 However the results of fused PET-CT are not usually as good as this.35 Again, a variety of FNAB techniques have been described, with essentially the same sensitivity and specificity as when used in the chemo-naïve setting. Thus restaging of the mediastinum after induction therapy in N2 disease remains a fraught subject, often requiring a complex step-wise approach with CT, PET-CT, trans-tracheal or esophageal FNAB, and repeat mediastinoscopy, and still with a risk of false-negative assessment of the mediastinum.35 As we have seen, tissue diagnosis is the ideal restaging tool, but it is difficult and, even in the best hands, it will always have a finite false-negative rate; it also requires heavy use of time and resources, and can submit the patient to multiple procedures. PET has been shown to be an alternative, or surrogate way to restage the mediastinum after induction therapy. Cerfolio et al have published two papers on an overlapping patient population, looking at the change in the SUV max on PET before and after induction chemotherapy.122,123 In the first study122 they demonstrated that a drop in SUV max of 80% in the primary tumor predicted a pathologic complete response with a sensitivity of 90%, a specificity of 100%, and an accuracy of 96%. These results are roughly as accurate as the best combined invasive restaging strategies. In the second study123 they showed that a drop in SUV max of 75% predicted complete response. If the SUV max in the mediastinal nodes decreased by 55% there was a very high chance of being a partial responder. The median decrease in SUV max was 100% (range 75–100%) in complete responders, 58% (range 2–100%) in patients who had a complete response in the N2 nodes but residual viable tumor in the primary tumor, and 32% (range ⫺5–82%) in patients with residual N2 disease. In terms of N2 disease, PET-CT was less reliable. A decrease of SUV max of >55% had a likelihood ratio of 9.1 in predicting clearance of the N2 nodes, but in reality residual N2 disease was missed by PET-CT in 13/65 patients (20%). One group studied the SUV max before and after induction

chemotherapy.124 These patients underwent induction chemotherapy followed by chemo-radiation therapy then surgery. A PET-CT was performed at time 0, after the chemotherapy (t1), and at the end of the induction process (t2). Patients with either a complete response or less than 10% viable tumor cells in the tumor had a drop in SUV max of 67% at t1 and 73% at t2. Follow-up was short so the survival data are difficult to interpret. Another group used PET to study the metabolic rate of glucose.125 The multivariate analysis showed that the absence of N2/N3 disease at PET had a survival hazard ratio of 2.33 (95% CI 1.04–5.22; p <0.04). Reading from the graphs, this translates into a three-year survival of a little under 0.6 for N2/N3 negative patients vs around 0.25 for those with N2/N3 disease. The hazard ratio for each 10% drop in the metabolic rate of glucose was 0.99 (95% CI 0.98–0.99; p <0.01). A residual metabolic rate of glucose after induction of ≤0.13 had a hazard ratio of 1.95 (95% CI 1.28–2.97; p <0.002). Again, looking at the graphs this translates into a threeyear survival of around 0.6 vs 0 for a value >0.013. Restaging with PET may also reveal previously undetected metastases after induction chemotherapy. This was seen in 9/47 patients in one study,126 and in 10/56 in another.127 The only alternative would be to try to stage the mediastinum with any of the variety of FNAB techniques, and, if that fails but there is a high index of clinical suspicion of N2 disease, administer induction chemotherapy to the patient. This would allow mediastinoscopy to be performed in an unscarred mediastinum, hopefully with a much higher sensitivity. However this approach is unvalidated at present. There is one important pitfall with the whole concept of offering patients induction chemotherapy. The harsh reality is that only 30–50% of patients will be downstaged and offered surgery, the rest going on to radical radiotherapy. This means that their chemo-radiation therapy will be sequential instead of concurrent, and there is a consensus now that concurrent chemoradiotherapy is the standard of care in stage IIIA and IIIB disease. The patient needs to be aware of this when consent is sought for induction therapy.

OTHER PROGNOSTIC INDICATORS Table 9.6 summarizes known or supposed prognostic factors in surgically resected NSCLC. Cell type is not per se a prognostic indicator,128 but as we have discussed previously certain cell types (adenocarcinoma and large

116 Textbook of Lung Cancer Table 9.6 Prognostic factors in surgically resected NSCLC Prognostic factors

Tumor related

Host related

Environment related

Essential

T category N category Extracapsular nodal extension Superior sulcus location Intrapulmonary metastases Histologic type Grade Vessel invasion Tumor size Molecular/biologic markers

Weight loss Performance status

Resection margins Adequacy of mediastinal dissection

Gender Age

Radiotherapy dose Adjuvant radiotherapy

Additional

New and promising

Quality of life Marital status

Published with kind permission of the editors and the UICC.129

cell poorly differentiated carcinoma) represent a risk factor for presenting at a higher stage of disease. The failure of screening to improve survival in a screened population129 is in part due to so so-called overdiagnosis of indolent disease, proving that the term indolent adenocarcinoma is not an oxymoron. Only performance status equals stage in its impact on survival after all treatment modalities. Others factors such as weight loss and the presence of systemic symptoms are accepted as important. Cell type, degree of differentiation, and vascular invasion may be significant, but reports vary depending upon stage and whether surgery was possible.130 Sex is a prognostic indicator – females have better survival independently of TNM stage and histology.131–133 Age has an impact on treatment but is not an independent variable. Certainly information on these factors should be recorded and data presented in any report of results. There is great interest in biologic markers in lung cancer, and the hope that a panel of markers, including oncogenes and tumor suppresser genes, can provide an independent, biologic method of anticipating outcome. At present our knowledge of these markers is imperfect, and there are still no markers that have translated into the clinical setting because they do not discriminate in a sufficiently robust way to allow therapeutic decisions to be made.130 It is recommended that, where possible, cryopreserved tissue from well-staged, surgical specimens should be stored for future studies. On-going smoking is increasingly found to have an effect on prognosis. All textbooks cite that the risk of developing a second primary lung cancer following

successful management of NSCLC is 1% per patientyear, and this is doubled if the patient continues to smoke. It is now starting to emerge that smoking can interfere with the effectiveness of radiotherapy.134 Similarly, smoking can reduce the effectiveness of chemotherapy upregulation of the pathways targeted by chemotherapy, thus inhibiting chemotherapy-induced apoptosis.135 Smoking has a particularly strong inhibitory effect on tyrosine-kinase inhibitors (TKIs). The BR.21 study on erlotinib in NSCLC showed that plasma concentrations of the drug were around twice as high in non-smokers and ex-smokers compared to current smokers. This is attributed to a lack of induction of cytochrome P450 1 A isoforms by cigarette smoke as well as a higher incidence of K-ras mutations in smokers resulting in faster plasma clearance of erlotinib in smokers.136 Genomics are starting to show promise in identifying patients at high risk of recurrence.137 It remains to be proven whether these patients will benefit from more aggressive postoperative chemotherapy. Similarly, ERCC1 is an enzyme that can repair the DNA damage induced by cisplatin. When cisplatin-based adjuvant chemotherapy was given to patients, those with tumors that were ERCC1-negative had a significantly longer survival than those with ERCC1-positive tumors.138 The SUV max also seems to indicate prognosis.139 When the SUV max is higher than 10, tumors tend to be more likely to be poorly differentiated and to present at a higher stage. For each stage, if the SUV max is greater than the median value seen for that stage this also tends to indicate a poorer prognosis – for example

Staging, classiﬁcation, and prognosis 117

in stage IB NSCLC the four-year survival was 80% for a SUV max lower than median, and only 66% when it was higher than the median (p = 0.048). These values were, respectively, 64% vs 32% (p = 0.028) for stage II and 64% vs 16% (p = 0.012) for stage IIIA.

PROGNOSIS The survival of patients with each stage of disease is discussed in detail in the chapters on treatment in this book, but a few comments are pertinent when considering staging. When reading the literature on the results of treatment of lung cancer, especially surgical series, the reader is reminded of two phenomena: what Shields has termed ‘the diminishing denominator’,140 and the impact of ‘stage migration’ or the Will Rogers effect.141 The diminishing denominator can give a false impression of the value of surgery in an advanced stage of lung cancer by reporting only the results on patients found to be within this stage at thoracotomy and surviving complete resection. Other patients are ‘censored’ from the analysis if found at thoracotomy not to fall into the study population, if resection is not possible, if incomplete resection has been performed, and even if dying after operation. The reported survival of patients in this stage who survive complete resection gives little guidance to the clinician armed only with cTNM, and results are further inflated by the use of actuarial survival statistics. Thus 300 patients with a presumptive advanced stage (IIIA for example) may proceed to thoracotomy. Eighty will be found to be in a lesser stage at thoracotomy, 60 will be technically irresectable (so-called open and close thoracotomy), 95 will undergo an incomplete resection (R1 or R2, as described in a previous section), and 15 will die after surgery. The analysis is thus restricted to the 50 patients who survived a complete resection for the designated advanced stage. Therefore the actuarial survival of the 10 who survive to five years after complete resection is computed to be 20%. Whilst this may impress the unwary, closer study reveals that more patients (15) will die of such unwarranted surgery than those in whom the prognosis is improved, at a cost of 220 major operations and much morbidity. Stage migration is an inevitable consequence of more detailed staging. As one refines the group under study, those eliminated usually cascade into the more advanced stages, swelling their numbers, although a few will prove to have less advanced stage disease. These new recruits to the higher stages have a better prognosis

than the original patients do in that group, defined by cruder staging techniques, and the prognosis of the group is thus improved. The shifting populations are evident in any study giving details of the results of surgery based upon cTNM and pTNM. In one study,142 the number of patients who fell into the T1N0 category fell from 349 to 264 when shifting from cTNM to pTNM and, conversely, the number of patients with T3N0 disease rose from 109 to 147. This demonstrates the improved staging achieved by thoracotomy. The fiveyear survival of patients based upon pTNM will always be superior to that based upon cTNM, and this effect is more pronounced in higher stage groups. In another study,2 the five-year survival of T1N0 patients rose from 61% to 67%, a 10% improvement, when moving from cTNM to pTNM, whilst survival of T3N0 patients rose from 22% to 38%, an improvement of 87% in the survival of this group. These statistical realities are legitimate, but one must resist the temptation to attribute the improved survival to the staging evaluation itself. The prognosis of NSCLC is very variable in different series. This is often a reflection of the rigor of both the pre- and intra-operative staging of the cancer. If pre-operative staging is not completely thorough there will be 10–20% undetected N2 disease at thoracotomy, provided that intra-operative staging has been done as it should. However, there are still many centers that do not routinely perform systematic nodal dissection (which in itself is a term which is often abused). A telltale sign is the five-year survival of stage I NSCLC. In properly staged patients this will be around 80%, down to around 65% when staging is less rigorous. Stage migration will then deploy its effects as stage progresses. When evaluating the benefits of any treatment for lung cancer it is important to study each paper carefully, to determine the true denominator, and to note all the tests used to define the population under study. Thus the reader may be better able to place into context the results reported in the following chapters.

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FURTHER READING Rami-Porta R, Ball D, Crowley J et al. on behalf of the International Staging Committee. The IASLC Lung Cancer Staging Project: proposals for the revision of the T Descriptors in the forthcoming (seventh) edition of the TNM classification for lung cancer. J Thorac Oncol 2007; 2: 593–602. Rusch VW, Crowley J, Giroux DJ et al. on behalf of the International Staging Committee on Cancer Research and Biostatistics. The IASLC Lung Cancer Staging Project: proposals for the revision of the N Descriptors in the forthcoming (seventh) edition of the TNM classification for lung cancer. J Thorac Oncol 2007; 2: 603–12. Postmus PE, Brambilla E, Chansky K et al. on behalf of the International Staging Committee. The IASLC Lung Cancer Staging Project: proposals for revision of the M Descriptors in the

forthcoming (seventh) edition of the TNM classification for lung cancer. J Thorac Oncol 2007; 2: 686–93. Groome PA, Bolejack V, Crowley JJ et al. on behalf of the International Staging Committee, Cancer Research and Biostatistics. The IASLC Lung Cancer Staging Project: validation of the proposals for revision of the T, N, and M Descriptors and consequent stage groupings in the forthcoming (seventh) edition of the TNM classification of malignant tumors. J Thorac Oncol 2007; 2: 694–705. Groome PA, Bolejack V, Crowley JJ et al. on behalf of the International Staging Committee, Cancer Research and Biostatistics. The IASLC Lung Cancer Staging Project: proposals for the revision of the TNM stage groupings in the forthcoming (seventh) edition of the TNM classification of malignant tumors. J Thorac Oncol 2007; 2: 706–14.

10 Treatment of non-small cell lung cancer 10.1 Treatment of NSCLC: surgery Robert J Korst Contents Introduction • Historical summary • Stage I disease (T1–2N0) • Stage II disease (T1–2N1 and T3N0) • Stage III disease • Stage IV disease • Special considerations • Palliative surgery • Summary

INTRODUCTION Lung cancer is one of the leading causes of cancer death worldwide. Approximately 80% of cases of newly diagnosed lung cancer are of the non-small cell type (NSCLC). Unfortunately, a large percentage of these patients will have inoperable disease on the basis of distant metastases (stage IV) or locally advanced disease (stage IIIB). For the remaining patients with early stage disease (stage I and II), as well as selected patients with locally advanced disease (stage IIIA), complete surgical resection remains the best hope for cure, provided that the operative risk is tolerable. Over the past four decades, several points regarding the conduct of resection have become accepted as the surgical management of NSCLC has evolved. First, incomplete resections leaving either gross or microscopic disease behind will fail to cure the disease and are rarely indicated in a palliative setting. Intraoperative frozen section analysis should be employed frequently to ensure negative margins. Second, general oncologic principles should be followed, including the resection of the tumor and surrounding normal lung (lobectomy or pneumonectomy) with draining lymphatics and lymph nodes. Third, the mediastinal lymph nodes should be dissected to accurately stage the patient, and fourth, en bloc resection of the tumor and surrounding structures is desirable whenever technically possible. Survival following surgical resection for NSCLC is stage-dependent (Table 10.1.1). Despite the development of the principles mentioned above, less than 15% of all patients can presently be expected to be cured of their disease. This dismal figure underscores the need for prevention as well as continued investigation into better treatment options for patients with NSCLC. HISTORICAL SUMMARY Although non-anatomic pulmonary resection for lung cancer had been reported in 1895, the first anatomic

lobectomy was performed by Davies in 1912. It was not until the advent of an effective underwater drainage system, however, that pulmonary resection could safely be performed on more of a routine basis. Following a report by Graham of the first pneumonectomy in 1933, surgical resection became the treatment of choice for lung cancer. Over the next several decades, various types of anatomic lung resections continued to be described, including segmentectomy, sleeve lobectomy, and pneumonectomy, as well as resection for superior sulcus tumors. Through the 1970s and 1980s, it became recognized that despite radical resection with negative margins, many patients with resected NSCLC ultimately died of their disease, with the majority of recurrences being distant metastases. This fact was especially true for patients found to have disease metastatic to the lymph nodes (locally advanced disease) at the time of resection. As a result of this observation, strategies which combine treatment modalities (surgery, chemotherapy, and radiation) are becoming more popular and are the subject of active investigation for nearly all stages of NSCLC. In addition, recent breakthroughs in the use of adjuvant chemotherapy following complete resection of NSCLC are changing the postoperative management of patients with this deadly disease. STAGE I DISEASE (T1–2N0) Patients with this early stage of NSCLC typically present without symptoms and most are cured with primary surgical excision. These tumors are usually peripheral in location and are discovered on a routine chest radiograph. These peripheral ‘coin lesions’ are mainly adenocarcinomas, or bronchioloalveolar carcinomas. Uncommonly, a radiographically ‘occult’ tumor may be discovered. Unlike the peripheral lesions, occult tumors are mainly squamous in histology and patients may present with hemoptysis. Not infrequently, occult tumors are detected during screening bronchoscopy after a previous lung

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Table 10.1.1 Survival following resection for NSCLC by stage (see text for references) Stage

Stage I Overall T1N0M0 T2N0M0 Stage II T1–2N1M0 T3N0M0 Chest wall invasion Mediastinal invasion Proximal bronchus Stage III N2 Clinically negative mediastinum Clinically positive mediastinum

Five-year survival (%)

76 84 68 47 56 29 36

34 9

cancer resection,1 or in patients who have undergone bronchoscopy as part of the work-up for another process, such as head and neck or esophageal cancer. Complete surgical excision is the treatment of choice for stage I NSCLC, provided the operative risk is acceptable. Patients should undergo preoperative pulmonary function testing to assess lung reserve, as well as cardiac evaluation if indicated from the patient’s history. The operation of choice is anatomic lobectomy. Occasionally, a more extensive resection needs to be performed when the location of the tumor is such that removal of a single lobe is not adequate. When the tumor protrudes into the mainstem bronchus, sleeve lobectomy is the procedure of choice to obtain negative bronchial margins; however, a tumor involving the bronchus intermedius usually requires a bilobectomy, while a lesion more extensively involving the mainstem bronchus requires pneumonectomy. Pneumonectomy may also be indicated in the rare circumstance when the tumor is closely associated with the proximal, extrapericardial pulmonary artery. For upper lobe lesions that invade the pulmonary artery to the lower lobe a vascular sleeve resection can be performed, sparing the lower lobe. Multiple series now suggest that sleeve resection for central tumors produces results similar to that seen with pneumonectomy from an oncologic standpoint.2,3 Although limited resections (wedge resection or segmentectomy) remain an option for patients with poor

pulmonary reserve, this practice should be avoided whenever possible due to the higher rate of local recurrence and trend toward decreased long-term survival when these lesser resections are performed, a standard set by the results of The Lung Cancer Study Group (LCSG) trial 821.4 In this study, patients with T1N0 NSCLC were randomized to undergo either lobectomy or limited resection (wedge resection or segmentectomy). Patients who underwent limited resection had a significantly higher rate of local recurrence than those in the lobectomy group, with a survival difference approaching statistical significance. However, in the modern era of lung cancer screening using computed tomography (CT), many tumors are detected while still very small (<1–2 cm). This observation, combined with the emergence of retrospective studies reporting excellent survival rates following limited resection for small, T1 lung cancers,5,6 suggests that a trial similar to LCSG 821 should be initiated to reset the standard for these very small, screen-detected tumors. Most anatomic pulmonary resections for stage I NSCLC have traditionally been performed using a posterolateral thoracotomy, during which a rib-spreading retractor is utilized. However, many surgeons now undertake these resections using a complete, videothoracoscopic (VATS) approach. The most commonly performed type of VATS resection involves the creation of two thoracoscopy ports as well as a 6–8 cm ‘utility’ incision, the latter used for dissection of the hilum as well as specimen retrieval. Multiple published reports have suggested that anatomic pulmonary resections can be performed safely, and are oncologically sound when performed via VATS for early-stage lung cancer.7,8 Additional benefits include less postoperative discomfort as well as decreased length of hospital stay with the VATS approach compared to open thoracotomy. As a result, VATS lobectomy has replaced its open counterpart for the management of stage I lung cancer in many centers. Although it has been suggested that mediastinal lymph node dissection is unnecessary in patients with very small T1 tumors, the vast majority of patients undergoing resection for NSCLC should have this procedure routinely performed. Although this approach has never definitively been shown to improve survival, it is the only way to accurately stage a patient’s disease, and adds very little time and morbidity to the operation. In addition, approximately 16% of patients with peripheral T1N0 tumors where the primary tumor is less than 3 cm in size will have mediastinal node metastases.9 When resecting a right-sided tumor, the right paratracheal, pretracheal, subcarinal, and inferior pulmonary

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ligament nodes should be dissected. On the left, the preaortic, aortopulmonary window, subcarinal and inferior pulmonary ligament nodes are accessible. Given the uncertain survival benefit of complete mediastinal lymph node dissection for early-stage NSCLC, a randomized trial conducted by The American College of Surgeons Oncology Group is currently underway to investigate this question. Operative mortality following pulmonary lobectomy for all stages of disease should not surpass 2%, but should be considerably less for patients with stage I disease. Morbidity and mortality increase with higher stages of disease and extended resections. Operative mortality following pneumonectomy is near 6% in most series, with some being even lower.10 The five-year survival for patients with completely resected T1N0 lesions surpasses 80% in some reports, while this figure is reduced to approximately 65% for T2N0 tumors. The overall five-year survival for patients with completely resected stage I NSCLC is approximately 75%.11 Recurrences following complete resection for stage I NSCLC are mainly in the form of distant metastases, as displayed in Table 10.1.2. No form of adjuvant therapy has traditionally been recommended for patients undergoing resection of stage I NSCLC. Recent randomized trials, however, have suggested a small survival benefit for patients with completely resected stage IB-III NSCLC. One of these, the National Cancer Institute of Canada Clinical Trials Group (NCIC) trial JBR.10, randomized 482 patients with stage IB or II NSCLC to either surgery alone or platinum-based adjuvant chemotherapy.13 Patients in the adjuvant therapy arm enjoyed significantly longer overall survival (69% vs 54% at five years) compared to those who underwent surgery alone. Despite this, mature results of the Cancer and Leukemia Group B (CALGB) 9633 trial, performed exclusively in stage IB patients, did not support these findings. CALGB 9633 randomized

Table 10.1.2 Sites of first distant recurrence following resection in 159 patients with stage I NSCLC lung cancer12 Site

Brain Lung Liver Bone Other Disseminated

Number

51 20 14 11 8 5

344 patients with stage IB NSCLC to either surgery alone or surgery followed by four cycles of paclitaxel/ carboplatin chemotherapy.14 No statistically significant difference in survival was noted between groups. As a result, the role of adjuvant chemotherapy in the management of patients with completely resected stage IB NSCLC remains controversial. Many clinicians will recommend adjuvant chemotherapy to these patients if their tumors appear to possess characteristics associated with a poor prognosis (e.g. tumors greater than 5 centimeters, vascular/lymphatic invasion). Adjuvant radiotherapy is currently not recommended for patients with completely resected stage I NSCLC, in light of the results of a meta-analysis showing that postoperative radiotherapy may increase mortality in these patients.15 Most clinicians would agree that patients require follow-up after resection for NSCLC; however, the nature of the follow-up regimen remains controversial. Given the poor prognosis associated with recurrent metastatic disease in patients who have undergone resection of NSCLC, follow-up regimens should probably be geared toward the detection of second primary lung cancer (SPLC), which occurs with an annual cumulative incidence of 2% per patient/year of follow-up.16 Recent published data suggest that serial computed tomography (CT) of the chest has the ability to detect SPLC while still in its early stages;17 however, the cost-effectiveness of this approach has not yet been substantiated.

STAGE II DISEASE (T1–2N1 AND T3N0) N1 disease Patients with T1–2N1 NSCLC represent a small subset in the spectrum of this disease, usually comprising less than 10% of patients coming to surgery. As with stage I, the majority of patients can be effectively treated with lobectomy, although about a third will require pneumonectomy, mainly due to involved hilar lymph nodes adherent to the pulmonary artery or major bronchi. Similar to stage I disease, it is important to perform a thorough mediastinal lymph node dissection in this group of patients, especially since there is a higher incidence of occult N2 disease. Recurrence following complete resection for T1–2N1 NSCLC is common, with five-year survival rates approaching only 45%.18 As with stage I, the most common form of recurrence is distant metastatic disease, especially if the tumor is an adenocarcinoma. Patients enjoying a better prognosis tend to be those with small primary tumors, squamous histology, and only one involved lymph node.

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T3N0 disease Chest wall involvement T3 tumors invading the chest wall are readily amenable to surgical resection. As a general guideline, one rib above and one below the gross margin of the tumor should be taken to ensure negative margins. Although en bloc resection is desirable and should be achieved whenever possible, discontinuous resection can be done when absolutely necessary as long as meticulous attention is paid toward documenting margins. It currently remains controversial whether a complete chest wall resection, including ribs, is necessary for tumors invading only the parietal pleura. A parietal pleurectomy with negative deep margins may be sufficient, but should be used with extreme caution. Following resection, the issue of chest wall reconstruction needs to be addressed. The first question regarding this is whether the chest wall reconstruction is really necessary, and this usually depends on the assessment of chest wall stability. After resection of short segments of one or two ribs, or up to three posterior segments under the paraspinous muscles or scapula, reconstruction is not usually necessary. When reconstruction is undertaken, the marlex/methylmethacrylate sandwich technique readily restores stability and prevents the flail chest phenomenon during