The association of cruciferous vegetables intake and risk of bladder cancer: a meta-analysis

This meta-analysis of cohort and case-control studies was undertaken to evaluate the relationship between cruciferous vegetables intake and risk of bladder cancer. Eligible studies were retrieved via both computer searches and review of references. The summary relative risks (RRs) with 95% confidence interval (CI) for the highest versus the lowest intake of cruciferous vegetables were calculated. Heterogeneity and publication bias were also evaluated. Five cohort and five case-control studies were included. A significantly decreased risk with bladder cancer was observed in overall cruciferous vegetables intake group (RR = 0.80; 95% CI 0.69-0.92) and subgroup of case-control studies (RR = 0.78; 95% CI, 0.67-0.89), but not in cohort studies (RR = 0.86; 95% CI, 0.61-1.11). No heterogeneity and publication bias were detected across studies. Our findings support that cruciferous vegetables intake was related to the decreased risk of bladder cancer. Because of the limited number of studies, further well-designed prospective studies are needed to explore the protective effect of cruciferous vegetables on bladder cancer.