ESR1 and breast cancer: Contemporary management of breast cancer with early detection, newer local control techniques, improved chemotherapy regimens, and targeted treatments has resulted in immense gains in survival in individuals with breast cancer.[1] Unfortunately, the triple negative breast cancers (TNBC) which are a subset of breast cancers clinically defined by the absence of the estrogen receptor (ER), progesterone receptor (PR), and Her 2 over expression, lack a therapeutic target and have a poor prognosis.