Coffee consumption and the risk of prostate cancer: the Ohsaki Cohort Study

BACKGROUND: Epidemiological evidence regarding the effect of coffee on the incidence of prostate cancer is inconsistent. We aimed to investigate coffee consumption and the risk of prostate cancer risk in a general Japanese population. METHODS: We conducted a prospective cohort study in Ohsaki city, Japan, where 18 853 men aged 40-79 years participated in a baseline survey. Coffee consumption was assessed via a validated self-administered questionnaire. During 11 years of follow-up (from January 1 1995 to December 31, 2005), 318 incident cases of prostate cancer were detected. The Cox proportional hazards regression model was used to calculate the hazard ratios (HRs) and 95% confidence interval (CIs). RESULTS: There was a significant inverse association between coffee consumption and the incidence risk of prostate cancer. Compared with those who did not drink coffee, the multivariate adjusted HRs were 0.81 (95% CI: 0.61-1.07), 0.73 (95% CI: 0.53-1.00), and 0.63 (095% CI: 0.39-1.00) for those who drank coffee occasionally, 1-2 cups per day, and > or =3 cups per day, respectively, with a P for trend of 0.02. CONCLUSION: This prospective finding from a Japanese population adds evidence that coffee intake is inversely associated with the incidence of prostate cancer.