Intake of milk and other dairy products and the risk of bladder cancer: a pooled analysis of 13 cohort studies

Background Inconsistent associations between milk and other dairy product consumption and bladder cancer (BC) have been reported. We aimed to investigate possible associations with BC risk for total and individual dairy products by bringing together the world's data on this topic. Methods Thirteen cohort studies, included in the BLadder cancer Epidemiology and Nutritional Determinants (BLEND) study, provided data for 3590 BC cases and 593,637 non-cases. Associations between milk and other dairy product consumption and BC risk were investigated using Cox proportional hazard regression analyses stratified by study center and adjusted for potential confounders. Results Overall, total 'other' dairy product consumption was not associated with BC risk (HR comparing highest with lowest tertile: 0.97 (95% CI: 0.87-1.07; p(trend) = 0.52) and likewise no association was observed for either liquid milk, processed milk, cream, cheese or icecream. However, an inverse association was observed between yoghurt consumption and BC risk when comparing those in the moderate (25-85 g/day) and high categories (>85 g/day) with non-consumers, with multivariate HR of 0.85 (95% CI: 0.75-0.96) and 0.88 (95% CI: 0.78-0.98), respectively. Conclusions We found no evidence of association between either total or individual dairy products and BC risk, but suggestive evidence that consumption of yoghurt may be associated with a decreased risk.