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

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

METHODS: This nested case-control study included 1,104 women from, the Women's Healthy Eating and Living Study, a multi-site randomized controlled trial. Cases (n=290) were women who died from 1995-2006. Matched controls (n=814) were 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 BC-specific mortality (BCM) using conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS: In fully-adjusted models, ACM ORs were elevated among women with PUFAs >median (versus ≤median) for α-linolenic acid (ALA, OR=1.63, 95%CI=1.18-2.24) and for linolenic acid (LA, OR=1.56, 95%CI=1.16-2.09), and 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 >median (versus ≤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), and PCFA-Factor 4 [ALA/GLA] scores >median (versus ≤median) were associated with increased odds of BCM (OR=1.47; 95%CI=1.04-2.09).

CONCLUSIONS: RBC ALA, LA, and GLA may be prognostic indicators among BC survivors.

IMPACT: These results are important for understanding the associations between a biomarker of PUFA intake and mortality among BC survivors.