Red Blood Cell Polyunsaturated Fatty Acids and Mortality Following Breast Cancer.

backgroundIntake of polyunsaturated fatty acids (PUFA) may affect mortality following breast cancer; however, epidemiological studies have relied on the self-reported assessment of PUFA intake. Herein, we examined the associations between red blood cell (RBC) PUFAs and mortality.

methodsThis nested case-control study included 1,104 women from the Women's Healthy Eating and Living study, a multistate randomized controlled trial. Cases (n = 290) comprised women who died from 1995 to 2006. Matched controls (n = 814) comprised women who were alive at the end of follow-up. PUFAs were measured in baseline RBC samples and included four ω-3 and seven ω-6 PUFAs. We examined each PUFA individually and principal components factor analysis (PCFA)-derived scores in association with all-cause mortality (ACM) and breast cancer-specific mortality (BCM) using conditional logistic regression to estimate ORs and 95% confidence intervals (CIs).

resultsIn fully adjusted models, ACM ORs were elevated among women with PUFAs above the median  (>median) versus at the median or below (≤median) for α-linolenic acid (ALA; OR = 1.63, 95% CI, 1.18-2.24) and linolenic acid (LA; OR = 1.56, 95% CI, 1.16-2.09). BCM ORs were elevated for ALA (OR = 1.83, 95% CI, 1.27-2.63), LA (OR = 1.70, 95% CI, 1.23-2.37), and γ-linolenic acid (GLA; OR = 1.50, 95% CI, 1.04-2.16). PCFA Factor 1 (arachidonic acid-adrenic acid-docosapentaenoic acid) scores above the median (vs. ≤median) were associated with lower odds of ACM (OR = 0.71, 95% CI, 0.52-0.97) and BCM (OR = 0.69, 95% CI, 0.49-0.97). PCFA Factor 4 (ALA/GLA) scores above the median (vs. ≤median) were associated with increased odds of BCM (OR = 1.47, 95% CI, 1.04-2.09).

conclusionsRBC ALA, LA, and GLA may be prognostic indicators among breast cancer survivors. IMPACT: These results are important for understanding the associations between a biomarker of PUFA intake and mortality among BC survivors.