Red meat, dietary nitrosamines, and heme iron and risk of bladder cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC)

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BACKGROUND: Previous epidemiologic studies found inconsistent results for the association between red meat intake, nitrosamines [NDMA: N-nitrosodimethylamine, and ENOC (endogenous nitroso compounds)], and the risk of bladder cancer. We investigated the association between red meat consumption, dietary nitrosamines, and heme iron and the risk of bladder cancer among participants of the European Prospective Investigation into Cancer and Nutrition (EPIC). METHODS: Data on food consumption and complete follow-up for cancer occurrence were available for a total of 481,419 participants, recruited in 10 European countries. Estimates of HRs were obtained by proportional hazard models, stratified by age at recruitment, gender, and study center and adjusted for total energy intake, smoking status, lifetime intensity of smoking, duration of smoking, educational level, and BMI. RESULTS: After a mean follow-up of 8.7 years, 1,001 participants were diagnosed with bladder cancer. We found no overall association between intake of red meat (log2 HR: 1.06; 95% CI: 0.99-1.13), nitrosamines (log2 HR: 1.09; 95% CI: 0.92-1.30 and HR: 0.98; 95% CI: 0.92-1.05 for ENOC and NDMA, respectively) or heme iron (log2 HR: 1.05; 95 CI: 0.99-1.12) and bladder cancer risk. The associations did not vary by sex, high- versus low-risk bladder cancers, smoking status, or occupation (high vs. low risk). CONCLUSIONS: Our findings do not support an effect of red meat intake, nitrosamines (endogenous or exogenous), or heme iron intake on bladder cancer risk.