ESR1 and breast carcinoma: Our patient was a 58-year-old Caucasian woman who had been diagnosed in September 1999 with estrogen receptor-positive (ER+), progesterone receptor-positive (PR+), human epidermal growth factor receptor 2/neu (Her2/neu)-negative ductal breast cancer assessed as American Joint Committee on Cancer stage IIA (pT1 pN1 M0 G1).