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Review
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| Asbestos and Colon Cancer: A Weight-of-the-Evidence Review John F. Gamble Exxon Biomedical Sciences, Inc., East Millstone, NJ 08875-2350 USA Abstract
What is the evidence that exposure to asbestos causes colon cancer? This weight-of-evidence review considers epidemiologic evidence from cohort studies of asbestos-exposed workers, case-control studies of colon cancer, animal bioassays, and other corroborative evidence. The major evidence for a causal association at high exposure is a combined colorectal standardized mortality ratio (SMR) of 1.5 for asbestos cohorts where the lung cancer SMR was greater than twofold. However, misdiagnosis may spuriously elevate the SMR. The strongest evidence against a causal association between colon cancer and asbestos exposure is the lack of an exposure-response gradient in asbestos cohorts where trends for lung cancer are observed. Population-based case-control studies of colon cancer do not show any consistent risk associated with asbestos exposure. Long-term ingestion studies show no evidence of an increased incidence of colon cancer in animals by this route of exposure and do not provide biological plausibility for a causal association between asbestos exposure and colon cancer. Key words: asbestos, colon cancer, colorectal cancer, gastrointestinal cancer, weight-of-evidence review. Environ Health Perspect 102:1038-1050 (1994) http://ehpnet1.niehs.nih.gov/docs/1994/102-12/gamble.html Address correspondence to J. F. Gamble, Exxon Biomedical Services, Inc., Mettlers Road, CN 2350, East Millstone, NJ 08875-2350 USA. Thanks to Vicki Fowler for typing and manuscript preparation. Received 7 April 1994 ; accepted 3 August 1994.
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