Consumption of vegetables and fruits and urothelial cancer incidence: a prospective study

Abstract

Although most epidemiological studies concerning urothelial cancer support a possible protective effect of vegetable and fruit consumption, previous studies have been inconsistent with regard to which vegetables and fruits may be responsible for an inverse association. The association between the consumption of 21 vegetables and nine fruits and urothelial cancer risk was assessed in the Netherlands Cohort Study among 120,852 men and women aged 55-69 years at baseline in 1986. After 6.3 years of follow-up, 538 incident cases and 2,953 subcohort members with complete vegetable data and 569 cases and 3,123 subcohort members with complete fruit data were available for case-cohort analyses. In multivariable case-cohort analyses, the following age-, sex-, and smoking-adjusted incidence rate ratios for groups of vegetable and fruit consumption were observed (comparing highest versus lowest quintile of consumption): total vegetables, 0.91 [95% confidence interval (CI): 0.65-1.27]; cooked vegetables, 0.98 (CI: 0.71-1.35); raw vegetables, 1.10 (CI: 0.78-1.53); cooked leafy vegetables, 0.89 (CI: 0.65-1.23); raw leafy vegetables, 0.94 (CI: 0.73-1.22); pulses, 1.03 (CI: 0.74-1.44); brassicas, 0.75 (CI: 0.54-1.04); allium vegetables, 0.89 (CI: 0.67-1.19); total fruit, 0.74 (CI: 0.53-1.04); and citrus fruit, 0.85 (CI: 0.62-1.17). For three separate items (cauliflower, cooked carrots, and mandarins), a statistically significant inverse association was seen, whereas for other specific vegetables or fruit, no statistically significant association was observed. The data are suggestive of an inverse association between the consumption of brassicas, total fruit, and urothelial cancer risk, whereas total vegetable consumption did not appear to be associated with urothelial cancer risk.