American Journal of Epidemiology 2005 162(9):868-878; doi:10.1093/aje/kwi285. Available online September 21, 3005. [Link]

Oluremi A. Aliyu1, Mark R. Cullen1, Matt J. Barnett2,3, John R. Balmes4,5, Brenda Cartmel1, Carrie A. Redlich1, Carl A. Brodkin3, Scott Barnhart3,6, Linda Rosenstock7, Leslie Israel8, Gary E. Goodman2,3,9, Mark D. Thornquist2,3 and Gilbert S. Omenn10,11

1 Yale Occupational and Environmental Medicine Program and the Cancer Center, Yale University School of Medicine, New Haven, CT
2 Fred Hutchinson Cancer Research Center, Seattle, WA
3 Occupational and Environmental Medicine Program, University of Washington, Seattle, WA
4 Department of Medicine, School of Medicine, University of California, San Francisco, San Francisco, CA
5 Center for Occupational and Environmental Health, University of California, Berkeley, Berkeley, CA
6 Harborview Medical Center, Seattle, WA
7 School of Public Health, University of California, Los Angeles, Los Angeles, CA
8 Center for Occupational and Environmental Health, University of California, Irvine, Irvine, CA
9 Swedish Medical Center Cancer Institute, Seattle, WA
10 Departments of Internal Medicine and Human Genetics, School of Medicine, University of Michigan, Ann Arbor, MI
11 Department of Public Health, School of Public Health, University of Michigan, Ann Arbor, MI


The relation between asbestos exposure and colorectal cancer remains controversial. The authors of this 1984–2004 US study examined the association among 3,897 occupationally exposed participants in the Beta-Carotene and Retinol Efficacy Trial (CARET) for chemoprevention of lung cancer, followed prospectively for 10–18 years. When a Cox stratified proportional hazards model was used, risks of colorectal cancer were elevated among male heavy smokers exposed to asbestos. Their relative risk was 1.36 (95% confidence interval: 0.96, 1.93) when compared with that for CARET heavy smokers not exposed to asbestos, after adjusting for age, smoking history, and intervention arm. The presence of asbestos-induced pleural plaques at baseline was associated with a relative risk of 1.54 (95% confidence interval: 0.99, 2.40); colorectal cancer risk also increased with worsening pulmonary asbestosis (p = 0.03 for trend). A dose-response trend based on years of asbestos exposure was less evident. Nonetheless, these data suggest that colorectal cancer risk is elevated among men occupationally exposed to asbestos, especially those with evidence of nonmalignant asbestos-associated radiographic changes.