Consumption of raw, but not cooked, cruciferous vegetables and reduction of bladder cancer risk Free

B47

Cruciferous vegetables contain isothiocyanates (ITCs), which show potent chemopreventive activity against bladder cancer in both in vitro and in vivo studies. However, previous epidemiological studies investigating cruciferous vegetable intake and bladder cancer risk have been inconsistent. Cooking can substantially reduce or destroy ITCs, and could account for study inconsistencies. In this hospital-based case-control study involving 275 individuals with incident, primary bladder cancer and 825 individuals without cancer, we examined usual pre-diagnostic intake of raw and cooked cruciferous vegetables in relation to bladder cancer risk. Odds ratios (OR) and 95% confidence intervals (CI) were estimated with unconditional logistic regression, adjusting for smoking and other bladder cancer risk factors. We observed a strong and statistically significant inverse association between bladder cancer risk and raw cruciferous vegetables (adjusted OR for highest vs. lowest category= 0.57, 95% CI = 0.38-0.84), with a clear dose-response trend (P = 0.004); there were no significant associations for fruit, total vegetables, or total cruciferous vegetables. The reduced risks observed for total raw crucifers were also observed for individual raw crucifer. The inverse associations were stronger in current smokers and heavy smokers. Risk reduction was greatest among non-smokers with three or more servings per month of raw cruciferous vegetables (adjusted OR = 0.27, 95% CI = 0.13-0.56). These data indicate that cruciferous vegetables, when consumed raw, may reduce risk of bladder cancer, a protective effect consistent with a role of dietary ITCs as chemopreventive agents against bladder cancer.