Adherence to the mediterranean diet and risks of prostate and bladder cancer in the Netherlands cohort study

Background: Prostate cancer and urinary bladder cancer are frequently occurring cancers with few risk factors identified. We examined the relation of Mediterranean diet (MD) adherence with risks of prostate and bladder cancer in the Netherlands Cohort Study (NLCS). Methods: Data were available for 58,279 men and 62,573 women, who completed a baseline questionnaire on diet and other cancer risk factors. Multiple MD scores, including the alternate Mediterranean diet score without alcohol (aMEDr), were calculated to assess MD adherence. After 20.3 years of follow-up, 3,868 prostate cancer cases (advanced: 1,256) and 1,884 bladder cancer cases could be included in multivariable Cox proportional hazards analyses. Results: aMEDr was not associated with advanced prostate cancer risk [hazard ratio (HR)_{per 2-point increment} (95% confidence interval, 95% CI) = 1.06 (0.96-1.17)]. In contrast, higher aMEDr values were associated with a significantly increased risk of nonadvanced prostate cancer (P_trend = 0.04). For bladder cancer risk, no association was observed with aMEDr [HR_{per 2-point increment} (95% CI) = 1.00 (0.92-1.09)]. Absolute scores based on the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) dietary recommendations were not associated with prostate or bladder cancer risk. Conclusions: MD adherence, measured by aMEDr or other MDscores, was not associated with decreased risks of advanced prostate cancer and bladder cancer in theNLCS. Higher levels of care-seeking behavior, screening attendance, and prostate cancer awareness in higher educated men with healthier lifestyles could potentially explain the positive associations observed for nonadvanced prostate cancer risk. Impact: MD adherence does not seem to reduce the risk of (advanced) prostate cancer or bladder cancer.