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Cancer Epidemiology: Principles and Methods
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International Agency for Research on Cancer
The International Agency for Research on Cancer (IARC) was established in 1965 by theWorld Health Assembly, as an independently financed organization within the framework ofthe World Health Organization. The headquarters of the Agency are at Lyon, France.
The Agency conducts a programme of research concentrating particularly on theepidemiology of cancer and the study of potential carcinogens in the human environment.Its field studies are supplemented by biological and chemical research carried out in theAgency’s laboratories in Lyon, and, through collaborative research agreements, in nationalresearch institutions in many countries. The Agency also conducts a programme for theeducation and training of personnel for cancer research.
The publications of the Agency are intended to contribute to the dissemination ofauthoritative information on different aspects of cancer research. Information about IARCpublications and how to order them is also available via the Internet at: http://www.iarc.fr/
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WORLD HEALTH ORGANIZATIONINTERNATIONAL AGENCY FOR RESEARCH ON CANCER
Cancer
Epidemiology:
Principles and
MethodsBy
Isabel dos Santos Silva
International Agency for Research on CancerLyon, France
1999
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Published by the International Agency for Research on Cancer,150 cours Albert Thomas, 69372 Lyon cédex 08, France
© International Agency for Research on Cancer, 1999
Distributed by IARCPress (fax: +33 04 72 73 83 02; E-mail: [email protected])and by the World Health Organization Distribution and Sales, CH-1211
Geneva 27 (fax: +41 22 791 4857)
Publications of the World Health Organization enjoy copyright protection in accordance with the provisions of Protocol 2 of the Universal Copyright Convention.
All rights reserved.
The designations employed and the presentation of the material in this publication do not implythe expression of any opinion whatsoever on the part of the Secretariat of the World Health
Organization concerning the legal status of any country, territory, city, or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by the World Health Organization in preference to others
of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters.
The authors alone are responsible for the views expressed in this publication.
The International Agency for Research on Cancer welcomes requests for permission to reproduce or translate its publications, in part or in full. Applications and enquiries should be
addressed to the Editorial & Publications Service, International Agency for Research on Cancer, which will be glad to provide the latest information on any changes made to the text, plans for new
editions, and reprints and translations already available.
IARC Library Cataloguing in Publication Data
dos Santos Silva, I.Cancer epidemiology: principles and methods / Isabel dos Santos Silva
1. Neoplasms – epidemiology I. Title
ISBN 92 832 0405 0 (NLM Classification W1)
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Contents
Foreword vii
About this book ix
1 Introduction to cancer epidemiology 1
2 Measurement of exposures and outcomes 11
3 Describing and presenting data 45
4 Measures of occurrence of disease and other 57health-related events
5 Overview of study designs 83
6 Evaluating the role of chance 103
7 Intervention trials 135
8 Cohort studies 165
9 Case-control studies 189
10 Cross-sectional surveys 213
11 Studies based on routine data 231
12 Introduction to survival analysis 263
13 Interpretation of epidemiological studies 277
14 Dealing with confounding in the analysis 305
15 Size of a study 333
16 Cancer prevention 355
17 The role of cancer registries 385
18 Designing, planning and conducting epidemiological research 405
References 427
Subject index 437
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Foreword
Within the IARC programme of training courses, high priority is givento courses on cancer epidemiology, particularly in countries of thedeveloping world. Population-based epidemiological studies are the onlyreliable source on the occurrence and outcome of cancer and form thebasis of any national or regional cancer control programme. Over theyears, the International Agency for Research on Cancer has been facedwith the problem of selecting an appropriate textbook for its courses. Toresolve this difficulty, we decided to publish a textbook suitable for thecourse faculty and the non-initiated reader. Isabel dos Santos Silva, fromthe London School of Hygiene and Tropical Medicine, a prominentepidemiologist with extensive teaching experience, has accomplished thistask admirably, in close consultation with external experts and an IARCAdvisory Board (see below).
We hope that this textbook will guide students and health professionalswishing to understand the basic principles and methods used in cancerepidemiology.
P. KleihuesDirector, IARC
IARC Advisory Board
Nubia MuñozD. Maxwell Parkin
Jacques EstèvePaolo Boffetta
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About this book
This book is addressed primarily to medical and public health students,clinicians, health professionals and all those seeking to understand theprinciples and methods used in cancer epidemiology. Its aim is not toconvert the readers into epidemiological experts but to make themcompetent in the use of basic epidemiological tools and capable ofexercising critical judgement when assessing results reported by others.
The book is designed to provide an easy understanding of the basicconcepts and methods through the use of illustrative examples, oftenusing real research data. It was my intention to ensure that the materialwould be accessible to everyone new to the field. Knowledge of statisticsis indispensable to the proper conduct, analysis and interpretation of epi-demiological studies. Thus, statistical concepts (and formulae) are alsopresented but the emphasis is on the interpretation of the data rather thanon the actual calculations.
The book is divided into 18 chapters. The first six introduce the basicprinciples of epidemiology and statistics. Chapters 7–13 deal in moredepth with each of the study designs and interpretation of their findings.Chapters 14 and 15 cover more complex statistical concepts and can beomitted at a first reading. Chapter 16 deals with methodological issues incancer prevention, including primary prevention, early detection(screening activities) and tertiary prevention. Chapter 17 reviews the roleof cancer registries in cancer epidemiology and prevention. Finally,Chapter 18 discusses logistic issues and practical considerations thatshould be taken into account in the design, planning and conduct of anytype of epidemiological research.
Few, if any, of the ideas and concepts in this book are original. Many ofthem derive from my own teaching experience at the London School ofHygiene and Tropical Medicine and, in particular, to my role as theorganizer of the School’s intensive course in epidemiology and medicalstatistics. I am deeply indebted to many colleagues and students withwhom I have worked over the past years for all I have learnt from them.It would be impossible for me to name all who, in one way or another,helped me to write this book—I can only hope that they are aware of myappreciation. I am, however, particularly grateful for the help of mycolleagues (and good friends) Bianca De Stavola and Esa Läärä for the longhours they spent reading earlier drafts and for their helpful comments,suggestions and stimulating discussions—I certainly learnt a lot from
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them! I would also like to thank IARC for giving me the opportunity towrite this book and, in particular, the members of the editorial committee(Drs Jacques Estève, Nubia Muñoz, Max Parkin and Paolo Boffetta), Dr.Rengaswami Sankaranarayanan and Dr. Martyn Plummer, for theirsuggestions and comments in the earlier stages of the project. I am alsograteful for all the support and encouragement given by my colleagues atthe London School of Hygiene and Tropical Medicine and, in particular,to the thoughtful comments on earlier versions of various chaptersprovided by Professor Peter Smith, Dr Noreen Maconochie and Dr PunamMangtani. I also wish to thank Ms Maria Quigley and Mr. Craig Higginsfor giving permission to include some of their teaching examples inChapter 14. Part of the material presented in Chapters 6 and 12 wasinitially developed as teaching material for our intensive course incollaboration with Dr Maconochie and Mr Jerry Wheeler—the stimulatingdiscussions we had at that time and the feedback received from ourstudents were very helpful in shaping those chapters. Lastly, I would liketo thank Dr John Cheney and Ms Helis Miido for all their editorialassistance.
Isabel dos Santos Silva
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