Fruit and vegetable intake and incidence of bladder cancer in a male prospective cohort.

BACKGROUND: Previous epidemiologic studies of fruit and vegetable intake and bladder cancer risk have yielded inconsistent results, especially with regard to the types of fruits and vegetables consumed. We examined total fruit and vegetable intake, as well as intakes of subtypes of fruits and vegetables, in relation to bladder cancer risk in a large male prospective cohort study.
METHODS: Two hundred fifty-two cases of incident bladder cancer were diagnosed from 1986 through January 31, 1996, among 47,909 men enrolled in the Health Professionals Follow-up Study. Each participant in this cohort completed a 131-item food-frequency questionnaire in 1986 and subsequently in 1990 and 1994. We used logistic regression analyses to examine fruit and vegetable intake in relation to bladder cancer risk, after adjusting for age, history of cigarette smoking, current smoking status, geographic region, total fluid intake, and caloric intake.
RESULTS: We observed a weak, inverse association that was not statistically significant between total fruit and vegetable intake and bladder cancer risk. Intake of cruciferous vegetables was inversely associated with risk (relative risk = 0.49; 95% confidence interval = 0.32-0.75, for the highest category of cruciferous vegetable intake compared with the lowest), but intakes of yellow or green leafy vegetables or carotenoid-rich vegetables were not associated with risk. Individual cruciferous vegetables, except for coleslaw, were all inversely related to bladder cancer risk, but only the associations for broccoli and cabbage were statistically significant.
CONCLUSIONS: Data from this study indicate that high cruciferous vegetable consumption may reduce bladder cancer risk, but other vegetables and fruits may not confer appreciable benefits against this cancer.