ESR1 and breast cancer: The study analyzed the prognostic power of four genomic signatures (Oncotype DXTM, Prosigna®, BCITM, and EndoPredict®) and two clinical scores (Clinical Treatment Score (CTS) and 4-gene immunohistochemical score (IHC4)) in two populations of postmenopausal patients with ER+ breast cancer and either 0 or 1 to 3 positive nodes.