ESR1 and breast cancer: The latest European School of Oncology/European Society of Medical Oncology (ESO/ESMO) consensus guidelines recommend that the 2020 ASCO/CAP acknowledgment that patients with tumors with ER staining between 1% and 10% represent a new reporting category with proximity to ER-negative BC, without solid data concerning the benefit from ET, should also be adopted for patients with metastatic BC with a low ER-positive status [56].