The effect of folate intake on ovarian cancer risk: A meta-analysis of observational studies

BACKGROUND: Previous publications studied the correction about folate intake and ovarian cancer risk, with inconsistent results. This meta-analysis aimed to explore the association between folate intake and ovarian cancer risk using the existing published articles. METHOD: We searched for relevant studies in electronic databases of PubMed, Web of Science, Embase, Cochrane, and Wanfang databases from inception to May 31, 2020. The overall relative risk (RR) and its 95% confidence intervals (95% CI) were pooled using a random-effect model. RESULTS: A total of 12 articles with 6304 ovarian cancer cases were suitable for the inclusion criteria. The evaluated of the ovarian cancer risk with total folate intake and dietary folate intake were reported in 6 articles and 10 articles, respectively. Overall, highest category of dietary folate intake compared with lowest category had nonsignificant association on the risk of ovarian cancer (RR = 0.90, 95% CI = 0.77–1.06). The association was not significant between total folate intake and ovarian cancer risk (RR = 1.06, 95% CI = 0.89–1.27). The results in subgroup analyses by study design and geographic location were not changed either in dietary folate intake analysis or in total folate intake analysis. CONCLUSION: Our meta-analysis demonstrates that folate intake had no significant association on the risk of ovarian cancer. Study design and geographic location were not associated with ovarian cancer while some other related factors were not investigated due to the limited information provided in each included study. Therefore, further studies are needed to verify our results.