ESR1 and breast cancer: For ER + /HER2- T1N0M0 BC, regardless of luminal-A-like qualities (strongly ER + and PR + , HER2-, with lower grade and proliferation markers) or luminal-B-like tumors, the BCC panel does not recommend adjuvant chemotherapy for patients with low genomic risk scores, according to the Oncotype DX and 70-gene signature tests (MammaPrint) [37–40].