Caffeine, Type of Coffee, and Risk of Ovarian Cancer: A Dose-Response Meta-Analysis of Prospective Studies

Context: Prospective studies on caffeine and different types of coffee intake in relation to the risk of ovarian cancer have shown conflicting results. Objective: The aim of the present study was to perform a dose-response meta-analysis of cohort studies on the association between dietary caffeine intake, different types of coffee consumption, and the risk of ovarian cancer. Data sources: PubMed/Medline, ISI Web of Science, Scopus, and EMBASE were searched to identify relevant studies reported until October 2018. Study selection: Prospective cohort studies that had considered caffeine or different types of coffee as the exposure variable and ovarian cancer as the main outcome variable or as one of the outcome variables were included in our systematic review and meta-analysis. Two of us independently screened 9344 publications. A total of 14 cohort studies were included in the meta-analysis. Data extraction: Two of us independently extracted the data. Any disagreements were resolved in consultation with the principal investigator. Results: Combining 13 effect sizes, we found no substantial association between coffee consumption and risk of ovarian cancer [risk ratio (RR), 1.08; 95% CI, 0.89 to 1.33]. Also, one additional cup daily of coffee consumption was marginally associated with an increased risk of ovarian cancer (RR, 1.02; 95% CI, 0.99 to 1.05; P = 0.21; I-2 = 0.0%; P-heterogeneity = 0.68). No statistically significant association was observed between caffeine intake or caffeinated or decaffeinated coffee consumption and the risk of ovarian cancer. Conclusions: We found no statistically significant association between caffeine intake or different types of coffee and the risk of ovarian cancer.