The immunohistochemical subtypes were defined as follows: HR+/HER2− indicates hormone receptor-positive, HER2-negative tumors; TNBC refers to triple-negative breast cancer (negative for estrogen receptor, progesterone receptor, and HER2); TPBC refers to triple-positive tumors (positive for both hormone receptors and HER2); and HR−/HER2+ includes tumors that are hormone receptor-negative and HER2-positive. The gene discussed is ESR1; the disease is triple-negative breast carcinoma.