Erythrocyte membrane n-3 polyunsaturated fatty acid are inversely associated with breast cancer risk among Chinese women.

The relationship between erythrocyte membrane n-3 polyunsaturated fatty acid (n-3 PUFA) and breast cancer risk is controversial. We aimed to examine the associations of erythrocyte membrane n-3 PUFA with odds of breast cancer among Chinese women by using a relatively large sample size. A case-control study was conducted including 853 newly diagnosed, histologically-confirmed breast cancer cases and 892 frequency-matched controls (5-year interval). Erythrocyte membrane n-3 PUFA were measured by gas chromatography. Logistic regression and restricted cubic spline were used to quantify the association between erythrocyte membrane n-3 PUFA and odds of breast cancer. Erythrocyte membrane α-linolenic acid (ALA), docosapentaenoic acid (DPA) and total n-3 PUFA were inversely and non-linearly associated with odds of breast cancer. The odds ratio (OR) values [95% confidence intervals (CIs)], comparing the highest with the lowest quartile (Q), were 0.57 (0.43-0.76), 0.43 (0.32-0.58) and 0.36 (0.27-0.49) for ALA, DPA and total n-3 PUFA, respectively. Erythrocyte membrane eicosapentaenoic acid (EPA) and docosahexaenoic acids (DHA) were linearly and inversely associated with odds of breast cancer [ (EPA: OR Q4 vs .Q1 (95% CI) = 0.59 (0.45-0.79); DHA: OR Q4 vs .Q1 (95% CI) = 0.50 (0.37-0.67)]. The inverse associations were observed between ALA and odds of breast cancer in postmenopausal women, and between DHA and ER+ breast cancer. This study showed that erythrocyte membrane total and individual n-3 PUFA were inversely associated with odds of breast cancer. Other factors, such as menopause and hormone receptor status, may warrant further investigation when examining the association between n-3 PUFA and odds of breast cancer.