Epidemiological studies have investigated the association between citrus fruit and bladder cancer risk; however, the results are inconsistent. To assess these issues, we conducted a meta-analysis of currently available studies. We identified relevant articles by searching the MEDLINE and EMBASE databases. We calculated the summary relative risk (RR) with 95% confidence interval (95% CI) using a random effect model. We included eight case-control studies and six cohort studies in the meta-analysis. There was a significant inverse association between citrus fruit intake and bladder cancer risk in all pooled studies (RR: 0.85; 95% CI, 0.76-0.94) and case-control studies (RR: 0.77; 95% CI, 0.64-0.92), but not in the cohort studies (RR: 0.96; 95% CI, 0.87-1.07). Our results suggest that citrus fruit intake is related to decreased bladder cancer risk. Subsequent well-designed, large prospective studies are needed to obtain better understanding of this relationship.

High adult height was positively associated with the risk of kidney cancer in both men and women in this meta-analysis. Future prospective studies are needed to determine the generalizability of these findings to non-Caucasians.