Smoking and colorectal cancer risk: data from the Melbourne Colorectal Cancer Study and brief review of literature.

Lifetime smoking data were obtained from 715 colorectal cancer cases and 727 age/sex matched community controls as one part of a large, comprehensive, population-based study of colorectal cancer aetiology and survival in Melbourne, Australia, The Melbourne Colorectal Cancer Study. Statistically significant associations were found for those males smoking handrolled cigarettes and for cigar-/pipe-smoking males with colon cancer. Review of 18 previous case control studies of colorectal cancer showed an elevated risk for cigar-smoking black males in one study, a statistically non-significant increased risk for current smokers in one of 3 cohort studies and a statistically significant elevation of risk for smokers in 2 of 3 studies of adenomatous large-bowel polyps. Although at present there is insufficient evidence to link smoking with large-bowel cancer, the possibility that ingested tobacco is in some way carcinogenic for the colorectal mucosa may be worth further study.