Serum Phospholipids Fatty Acids and Breast Cancer Risk by Pathological Subtype.

This study evaluates whether serum phospholipids fatty acids (PL-FAs) and markers of their endogenous metabolism are associated with breast cancer (BC) subtypes. EpiGEICAM is a Spanish multicenter matched case-control study. A lifestyle and food frequency questionnaire was completed by 1017 BC cases and healthy women pairs. Serum PL-FA percentages were measured by gas chromatography-mass spectrometry. Conditional and multinomial logistic regression models were used to quantify the association of PL-FA tertiles with BC risk, overall and by pathological subtype (luminal, HER2+ and triple negative). Stratified analyses by body mass index and menopausal status were also performed. Serum PL-FAs were measured in 795 (78%) pairs. Women with high serum levels of stearic acid (odds ratio (OR) = 0.44; 95% confidence interval (CI) = 0.30-0.66), linoleic acid (OR = 0.66; 95% CI = 0.49-0.90) and arachidonic to dihomo-γ-linolenic acid ratio (OR = 0.64; 95% CI = 0.48-0.84) presented lower BC risk. Participants with high concentrations of palmitoleic acid (OR = 1.65; 95% CI = 1.20-2.26), trans-ruminant palmitelaidic acid (OR = 1.51; 95% CI = 1.12-2.02), trans-industrial elaidic acid (OR = 1.52; 95% CI = 1.14-2.03), and high oleic to stearic acid ratio (OR = 2.04; 95% CI = 1.45-2.87) showed higher risk. These associations were similar in all BC pathological subtypes. Our results emphasize the importance of analyzing fatty acids individually, as well as the desaturase activity indices.