ESR1 and breast cancer: Triple negative breast cancers, defined by the lack of estrogen receptor (ER), progesterone receptor (PR) and epidermal growth factor receptor 2 (Her2/cerbB2/EGFR2) expression, account for 10 to 20% of all breast carcinomas in Asian and Western populations [1-7], but occur at much higher frequencies in individuals of African descent [1-3,8].