Five intrinsic subtypes of breast cancer were initially identified: Luminal-A, Luminal-B, HER2+, triple negative/basal like (TNBC) and normal like, which is based on the gene expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) (2). Here, ESR1 is linked to breast carcinoma.