Meat intake and risk of bladder cancer: a meta-analysis

Meat consumption is inconsistently associated with the development of bladder cancer in several epidemiological studies. We performed a meta-analysis of evidence for relationships of meat consumption with risk of bladder cancer. Literature searches were conducted to identify peer-reviewed manuscripts published up to October 2010. Twenty publications from 10 cohort studies and 11 case-control studies were included in the analyses. We quantified associations with bladder cancer using meta-analysis of relative risk (RR) associated with the highest versus the lowest category of meat intake using random effect model. Pooled results indicate that overall meat intake was not related to the risk of bladder cancer (RR = 1.04, 95% CI = 0.80-1.27), while high red and processed meat consumer had a significantly increased 17 and 10% risk, respectively, when comparing the highest with the lowest category of meat intake. In subgroup analyses, studies conduced in Unites States/Canada exhibited a positive relationship between high meat intake and bladder cancer risk, and studies using self-administered questionnaires for exposure assessment also showed a significant increased relative risk for high meat consumers. However, because of borderline significance and small number of publications in individual analyses, more studies, particularly well-designed prospective studies, are needed to confirm these findings.