Background Although in vitro and in vivo experiments have suggested that coffee may exert inhibitory effects on prostate carcinogenesis, epidemiological studies have reported inconsistent results on the association between coffee consumption and prostate cancer.
Methods We conducted a meta-analysis of cohort studies to assess the association between coffee consumption and prostate cancer risk. PubMed and Embase were searched for eligible studies up to Jan 2020. Study-specific risk estimates were combined using fixed or random effects models depending on whether significant heterogeneity was detected.
Results Fifteen prospective cohort studies, with 50,200 cases of prostate cancer and 949,752 total cohort members, were included in the meta-analysis. A statistically significant inverse association was detected between coffee consumption and prostate cancer risk. The pooled relative risk (RR) was 0.91 (95% CI: 0.84, 0.98; I 2= 53.2%) for the highest coffee consumption compared with lowest consumption. The association exhibited a linear trend ( P =0.006 for linear trend), and the pooled RR was 0.989 (95% CI: 0.982, 0.997) for an increase of 1 cup of coffee per day. The pooled RRs were 0.93 (95% CI: 0.87, 0.99), 0.88 (95% CI: 0.71, 1.09) and 0.84 (95% CI: 0.66, 1.08) for localized, advanced and fatal prostate cancer, respectively. No publication bias was detected.
Conclusions Our findings provide more evidence that increased coffee consumption is associated with lower prostate cancer risk. It implies that men might be encouraged to increase the coffee intake to lower their risk of prostate cancer.