Gynecological cancer and omega-3 fatty acid intakes: Meta-analysis.

BACKGROUND AND OBJECTIVES: Previous observational epidemiological studies have reported inconsistent findings on the association between dietary intake of omega-3 fatty acids and endocrine-related gynecological cancer including ovarian cancer and endometrial cancer. This study aimed to investigate this association using a metaanalysis of observational studies. METHODS AND STUDY DESIGN: We searched PubMed, EMBASE, and Cochrane library by using keywords related to the topic in December 2019. The pooled odd ratios (pORs), pooled relative risks (pRRs), or pooled hazard ratios (pHRs) with 95% confidence intervals (CIs) were calculated based on a random- effects model. Also, we performed subgroup analyses by methodological quality, type of cancer, study design, and type of omega-3 fatty acids. RESULTS: A total of 10 observational studies with six case-control and four prospective cohort studies were included in the current meta-analysis. In the meta-analysis of all studies, dietary intake of omega-3 fatty acids was not significantly associated with the risk of endometrial and ovarian cancers (pOR/HR, 0.87; 95% CI, 0.73-1.04; I2=67.2%) (highest versus lowest intake). In the subgroup analysis by type of study, no significant association was found in cohort studies (pHR, 1.03; 95% CI, 0.63-1.67, I2=81.9%), whereas dietary intake of omega-3 fatty acids was associated with the decreased risk of endocrine-related gynecological cancers in case-control studies (pOR, 0.81; 95% CI, 0.67 to 0.98, I2=55.7%). CONCLUSIONS: The current metaanalysis of observational studies suggests that dietary intake of omega-3 fatty acids is not significantly associated with the risk of endocrine-related gynecological cancer.