ERBB2 and breast cancer: They discriminated eBC and aBC patients using an OPLS model calculated on serum NMR spectra with 89.8% sensitivity, 79.3% specificity, and 84.1% accuracy, in a mostly postmenopausal population (mean age 56 and 57 years for eBC and aBC patients, respectively), with ER-positive HER2-negative breast cancer.