Cigarette Smoking and Colorectal Carcinoma Mortality in a Cohort with Long-Term Follow-Up

BACKGROUND. Evidence suggests that colorectal carcinoma (CRC) may be a tobacco-associated malignancy. METHODS. In the current study, the authors examined the association between cigarette smoking and CRC mortality in the Chicago Heart Association Detection Project in Industry study, a cohort of 39,299 men and women with an average of 26 years of follow-up. To assess whether the association was stronger in participants with a potentially long history of smoking, the authors also stratified the analysis using a baseline age ≥ 50 years versus < 50 years. RESULTS. Using multivariate Cox regression analysis, there was a marginally significant trend (P = 0.06) for men and women combined between smoking and CRC mortality. In the age-stratified analysis in the older participant group, there was no apparent association for men, women, or men and women combined. In the younger participant group, there appeared to be dose-response relations for women and for men and women combined (P value for trend = 0.008 and 0.03, respectively) between smoking and CRC mortality. The relative risk for women who smoked >20 cigarettes/day compared with never smokers was 2.49 (95% confidence interval [95% CI], 0.87-7.12), and was 1.87 for men and women combined (95% CI, 1.08-3.22). CONCLUSIONS. The results of the current study support an association between cigarette smoking and CRC mortality, particularly in women age < 50 years.