Association of serum phospholipid fatty acids with breast cancer risk among postmenopausal cigarette smokers

To examine the association between breast cancer risk and the fatty acid composition of phospholipids in prediagnostic serum samples. We analyzed the fatty acid composition in 130 incident postmenopausal breast cancer cases and 257 matched controls nested within the beta-Carotene and Retinol Efficacy Trial Cohort. The fatty acid composition was measured by gas chromatography. Multivariate-adjusted odds ratios and corresponding 95% confidence intervals for the risk of breast cancer were estimated using logistic regression. Stratified analysis was conducted by smoking status. There were no associations with breast cancer risk for total saturated, monounsaturated, n-3, n-6, or trans fatty acids among all women. For individual fatty acids, we observed an inverse association with the trans linoleic acid, 18:2n6tt (p (trend) = 0.0002). Among current smokers, long-chain saturated fatty acids (22:0 and 24:0) and total 16:1 trans fatty acids were positively associated with the risk of breast cancer, whereas these fatty acids showed no association among former smokers. Overall, we observed no significant association between serum phospholipid fatty acids and breast cancer risk, except for the trans linoleic acid isomer 18:2n6tt, which was unexpected. Our finding of a positive association of long-chain saturated fatty acids (22:0 and 24:0) and total 16:1 trans fatty acids with the risk of breast cancer only in current smokers may suggest an effect modification by smoking status. Our findings need to be replicated in future epidemiologic studies.