ESR1 and triple-negative breast carcinoma: According to different expression statuses of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2), and Ki-67, IDC patients could be classified into different molecular subtypes, including Luminal A, Luminal B, HER-2 enriched, and triple-negative breast cancer (TNBC) [18].