The association between meat and fish consumption and bladder cancer risk: a pooled analysis of 11 cohort studies

Evidence on the effects of meat consumption from different sources on the risk of bladder cancer (BC) is limited and controversial. Therefore, this study aimed to evaluate the associations between meat consumption and BC risk using a pooled data approach. Individual data from 11 prospective cohorts comprising 2848 BC cases and 515,697 non-cases with a total of 5,498,025 person-years of follow-up was pooled and analysed to investigate the potential associations between total red meat and products, red meat, processed meat, poultry and total fish and BC risk. Hazard ratios (HRs), with corresponding 95% confidence intervals (CIs), were estimated using Cox regression models stratified on cohort. Overall, an increased BC risk was found for high intake of organ meat (HR comparing highest with lowest tertile: 1.18, 95% CI: 1.03, 1.36, p-trend = 0.03). On the contrary, a marginally inverse association was observed for total fish intake and BC risk among men (HR comparing highest with lowest tertile: 0.79, 95% CI 0.65, 0.97, p-trend = 0.04). No associations were observed for other meat sources. Results of this prospective study suggest that organ meat consumption may be associated with BC development. Replication in large-scale prospective studies and investigation of possible causal mechanisms is needed. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10654-021-00762-4.