Dietary Omega-3 and Omega-6 Fatty Acid Intake and Breast Cancer Risk: A Systematic Review and Meta-Analysis of Cohort Studies.

Breast cancer remains the most commonly diagnosed malignancy among women worldwide. Although dietary fatty acids have been widely investigated, the relationship between polyunsaturated fatty acids intake and breast cancer risk remains unclear. This study aimed to conduct a systematic review and meta-analysis of cohort studies to elucidate the association between higher dietary intake of omega-3 (ω-3) and omega-6 (ω-6) fatty acids and breast cancer risk. A systematic search of major databases was conducted up to January 2026 to identify eligible cohort studies. Random-effects models were used to pool multivariable-adjusted effect sizes (ESs). Heterogeneity was assessed using the I2 statistic, and publication bias was evaluated using Begg's and Egger's tests. Sixteen studies on ω-3 and 18 on ω-6 were included. ω-3 intake was not significantly associated with breast cancer risk (ES: 0.97; 95% CI: 0.92-1.02; p = 0.248; I2 = 10.2%). ω-6 intake also demonstrated no significant overall effect (ES: 1.03; 95% CI: 0.97-1.10; p = 0.384; I2 = 43.9%). Subgroup analyses revealed regional variability, with American studies showing a significant, small inverse association with ω-6 intake (ES: 0.95; 95% CI: 0.92-0.98; p = 0.002). Sensitivity analyses confirmed the robustness of findings, and funnel plots indicated no substantial publication bias. This meta-analysis found no significant association between higher dietary intake of ω-3 or ω-6 and the risk of breast cancer.