Urinary bladder cancer risk factors in Egypt: a multicenter case-control study.

BACKGROUND We investigated associations between tobacco exposure, history of schistosomiasis, and bladder cancer risk in Egypt. METHODS We analyzed data from a case-control study (1,886 newly diagnosed and histologically confirmed cases and 2,716 age-, gender-, and residence-matched, population-based controls). Using logistic regression, we estimated the covariate-adjusted ORs and 95% confidence interval (CI) of the associations. RESULTS Among men, cigarette smoking was associated with an increased risk of urothelial carcinoma (OR = 1.8; 95% CI, 1.4-2.2) but not squamous cell carcinoma (SCC); smoking both water pipes and cigarettes was associated with an even greater risk for urothelial carcinoma (OR = 2.9; 95% CI, 2.1-3.9) and a statistically significant risk for SCC (OR = 1.8; 95% CI, 1.2-2.6). Among nonsmoking men and women, environmental tobacco smoke exposure was associated with an increased risk of urothelial carcinoma. History of schistosomiasis was associated with increased risk of both urothelial carcinoma (OR = 1.9; 95% CI, 1.2-2.9) and SCC (OR = 1.9; 95% CI, 1.2-3.0) in women and to a lesser extent (OR = 1.4; 95% CI, 1.2-1.7 and OR = 1.4; 95% CI, 1.1-1.7, for urothelial carcinoma and SCC, respectively) in men. CONCLUSIONS The results suggest that schistosomiasis and tobacco smoking increase the risk of both SCC and urothelial carcinoma. IMPACT This study provides new evidence for associations between bladder cancer subtypes and schistosomiasis and suggests that smoking both cigarettes and water pipes increases the risk for SCC and urothelial carcinoma in Egyptian men.