ABSTRACT
There is no doubt that asbestos-for example, amphibole asbestos such as crocidolite and amosite, and Canadian chrysotile-can cause lung cancer, most often in combination with cigarette smoke (causal coaction), and the International Agency for Research on Cancer has classi“ed asbestos as a Group 1 carcinogen (i.e., a proven human carcinogen). It is also widely accepted that
CONTENTS
6.1 Introductory Comments on Asbestos-Related Lung Cancer ................................................269 6.2 General Characteristics of Asbestos-Associated Lung Cancer ............................................ 271 6.3 Synergy between Cigarette Smoke and Asbestos for the Causation of Lung Cancer:
Human and Experimental Evidence ..................................................................................... 273 6.4 Latency Intervals between Asbestos Exposure and Lung Cancer........................................ 275 6.5 Asbestosis and Lung Cancer: The Fibrosis-Cancer Hypothesis .......................................... 276 6.6 The Occurrence of Lung Cancer in the Setting of Nonasbestos Interstitial Lung
Disease and COPD ............................................................................................................... 278 6.7 The Anatomic Distribution of Asbestosis and Asbestos-Related Lung Cancers .................280 6.8 Is Asbestosis a “Consistent and Reliable” Marker for Attribution of Lung Cancer to
Asbestos? ..............................................................................................................................280 6.9 Estimates of Cumulative Asbestos Exposure and Asbestosis .............................................. 283 6.10 The Cumulative Exposure Model for Lung Cancer Causation by Asbestos ........................ 283 6.11 The Cumulative Exposure Model and the Helsinki Criteria ................................................290 6.12 Criticisms of the Helsinki Criteria ........................................................................................ 291 6.13 General Acceptance of the Cumulative Exposure Model and the Delphi Study
Reported by Banks et al. .......................................................................................................294 6.14 Is a Relative Risk of 2.0 or More Necessary to Attribute Lung Cancer to Asbestos? .......... 295 6.15 A Modi“ed Set of Criteria for Attribution ............................................................................296 6.16 Conclusion ............................................................................................................................297 References ......................................................................................................................................299
tobacco smoke and asbestos in combination play a more than additive causal role for lung cancer induction-that is, a synergistic effect by way of a multiplicative or submultiplicative interaction (see later discussion). Yet the criteria for causal attribution of lung cancer to asbestos have been beset with controversy for decades: disagreement has focused on the issue of whether asbestosis is an obligate precursor for assignment of causation or whether lung cancer can be attributed on the basis of cumulative asbestos exposure, with no requirement for asbestosis.1 Recent reviews2-5 have revisited this issue and at least two2,4 concluded that asbestosis is the only “consistently reliable marker”2 for asbestos-attributable lung cancer. This chapter concentrates on classic studies and recent literature on this subject.*
