Cigarette smoking and risk of bladder, pancreas, kidney, and colorectal cancers in Iowa

PURPOSE: Although there are numerous reports on the effects of cigarette smoking and cancer, they have infrequently compared risks at more than one cancer site after multivariate adjustment. We analyzed data from a population-based case-control study that included five anatomic sites to evaluate the association between cigarette smoking and each cancer site and to rank the associations by site. METHODS: Study respondents included 1452 bladder, 406 kidney, 376 pancreatic, 685 colon, and 655 rectal cancer cases, as well as 2434 population controls. A self-administered questionnaire was used to collect information on cigarette smoking and other potential confounders including occupation, drinking water source, and dietary practices. Logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), after adjustment for age, total energy intake, and other site- and sex-specific confounders. RESULTS: In both sexes, cigarette smoking (ever vs. never) was associated with risk of bladder cancer (OR = 2.5; 95% CI, 2.0-3.1 for males; OR = 2.7; 2.0-3.6 for females) and pancreatic cancer (OR = 1.8; 1.2-2.8 for males; OR = 2.1; 1.4-3.1 for females). Cigarette smoking also increased the risk of kidney cancer among males (OR = 1.8; 1.3-2.7), and to a lesser degree, among females (OR = 1.2; 0.8-1.8). No association was found for colon or rectal cancer in either sex. CONCLUSIONS: Cigarette smoking increased the risk of bladder, kidney, and pancreatic cancer in men and women. The rankings of multivariate-adjusted ORs from highest to lowest were bladder, pancreas, kidney, and colorectum, with little difference between men and women.