Coffee consumption and prostate cancer risk: an updated meta-analysis

Many epidemiological studies have been conducted to explore the association between coffee consumption and prostate cancer. However, the results remain inconsistent. We performed a large meta-analysis of relevant studies to derive a more precise estimation of this relationship. Systematic searches of PubMed and several other databases up to June 2013 were retrieved. All epidemiologic studies regarding coffee consumption and prostate cancer risk were included, and odds ratios (ORs) with 95 % confidence intervals (CIs) were calculated to estimate the strength of the association. Twelve case-control studies involving 7,909 prostate cancer cases and 9,461 controls and nine cohort studies involving 455,123 subjects were included in our analysis. Compared with the lowest category, the unstratified highest category of coffee consumption showed a significance reduction in prostate cancer risk of a fixed-effects model (OR 0.91, CI 0.86-0.97). A borderline significant influence was also found when the stratified highest category (US a parts per thousand yen4, Europe a parts per thousand yen5) of coffee consumption was compared with the reference category (OR 0.96, CI 0.92-1.00), but no relationships were observed for the other two categories. In another analysis conducted by coffee consumption and prostate cancer stage and Gleason grade, our results showed a significant inverse association in all categories of prostate cancer except Gleason < 7 grade in a fixed-effects model; the results remained the same, except for advanced prostate cancer, in a random-effects model. Our meta-analysis suggests that high (e.g., highest a parts per thousand yen4 or 5 cups/day) coffee consumption may not only be associated with a reduced risk of overall prostate cancer, but also inversely associated with fatal and high-grade prostate cancer.