Alcohol consumption, finasteride, and prostate cancer risk: results from the Prostate Cancer Prevention Trial.

Background: Current research is inconclusive regarding the relation between alcohol consumption and prostate cancer risk. In this study, the authors examined the associations of total alcohol, type of alcoholic beverage, and drinking pattern with the risk of total, low-grade, and high-grade prostate cancer.

Methods: Data for this study came from the 2129 participants in the Prostate Cancer Prevention Trial (PCPT) who had cancer detected during the 7-year trial and 8791 men who were determined by biopsy to be free of cancer at the trial end. Poisson regression was used to calculate relative risks (RRs) and 95% confidence intervals (95% CIs) for associations of alcohol intake with prostate cancer risk.

Results: Associations of drinking with high-grade disease did not differ by treatment arm. In combined arms, heavy alcohol consumption (> or =50 g of alcohol daily) and regular heavy drinking (> or =4 drinks daily on > or =5 days per week) were associated with increased risks of high-grade prostate cancer (RR, 2.01 [95% CI, 1.33-3.05] and 2.17 [95% CI, 1.42-3.30], respectively); less heavy drinking was not associated with risk. Associations of drinking with low-grade cancer differed by treatment arm. In the placebo arm, there was no association of drinking with risk of low-grade cancer. In the finasteride arm, drinking > or =50 g of alcohol daily was associated with an increased risk of low-grade disease (RR, 1.89; 95% CI, 1.39-2.56); this finding was because of a 43% reduction in the risk of low-grade cancer attributable to finasteride treatment in men who drank <50 g of alcohol daily and the lack of an effect of finasteride in men who drank > or =50 g of alcohol daily (P(interaction) = .03).

Conclusions: Heavy, daily drinking increased the risk of high-grade prostate cancer. Heavy drinking made finasteride ineffective for reducing prostate cancer risk.