Stratification by breast cancer subtypes for all metabolites (see Additional file 1: Figure S2) showed that no metabolite reached statistical significance after correction for multiple testing in each subtype, although for ER+PR+/−HER2− cases (n = 1084 cases), PC ae C36:3 and PC aa C36:3 had adjusted P values close to statistical significance (0.066 and 0.074, respectively). Here, PGR is linked to breast cancer.