Abstract 634: Dietary flavonoid intake, black tea consumption, and prostate cancer risk

Abstract

Abstract Background: Flavonoids are natural antioxidants that may have anticarcinogenic activity. These compounds are found in different foods of plant origin. A major source of flavonoids is black tea. We investigated associations between specific dietary flavonoid intakes, black tea consumption, and risk of prostate cancer and prostate cancer subgroups based on disease stage. Methods: We conducted a case-cohort study among 58,279 men in the Netherlands Cohort Study. Cohort members completed a baseline questionnaire on dietary habits and lifestyle. Person-years at risk were estimated by a subcohort randomly sampled at baseline. From 1986 to 2003, 3,451 prostate cancer patients were identified including 781 patients with non-advanced cancer (Union for International Cancer Control (UICC) stage I or II) and 1,196 patients with advanced cancer (UICC stage III or IV). Of these advanced prostate cancers, 753 were stage IV prostate cancers. Flavonoid contents in foods and beverages were derived from food composition tables based on data gathered in the Netherlands. We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). All tests were two-sided. Results: Intakes of the flavonoids catechin, kaempferol, and myricetin were inversely associated with risk of stage IV prostate cancer. Intakes of epicatechin and “gallates” (catechins typical of tea) and consumption of black tea were associated with a decreased risk of both advanced and stage IV prostate cancer. None of these intakes were associated with overall or non-advanced prostate cancer risk. Hazard ratios of advanced and stage IV prostate cancer for the highest versus the lowest category of black tea consumption (Δ5 versus β1 cups per day) were 0.73 (95% CI = 0.58-0.92) and 0.64 (95% CI = 0.49-0.85) respectively. When adjusted for black tea consumption, associations between specific flavonoid intakes and advanced and stage IV prostate cancer risk were non-significant except for epicatechin intake. Hazard ratios of advanced and stage IV prostate cancer for the highest versus the lowest quartile of epicatechin intake were 0.79 (95% CI = 0.64-0.99) and 0.71 (95% CI = 0.54-0.92) respectively. In analyses stratified by smoking status we observed inverse associations between black tea consumption (Δ5 versus β1 cups per day) and risk of stage IV prostate cancer among former smokers (HR = 0.63, 95% CI = 0.43-0.93) and current smokers (HR = 0.41, 95% CI = 0.21-0.77) but not among never smokers. Conclusions: This large prospective cohort study showed that epicatechin intake and black tea consumption were associated with a decreased risk of advanced and stage IV prostate cancer but not overall or non-advanced prostate cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 634. doi:1538-7445.AM2012-634