ESR1 and breast carcinoma: Here breast cancer was graded into stage 1, 2, 3, and 4, and based on the histological subtype, it was classified into estrogen receptor (ER)-negative and ER-positive, progesterone receptor (PR)-negative and PR-positive, human epidermal growth factor receptor 2 (HER2)-negative and HER2-positive, as well as Triple negative breast cancer (TNBC) subgroups.