For example, patients are often treated with endocrine therapy or combined chemotherapy when the tumor is estrogen receptor/progesterone receptor (ER/PR)‐positive or treated with human epidermal growth factor receptor 2‐(HER2) targeted drugs (trastuzumab or pertuzumab) or concurrent chemotherapy when the tumor is HER2 positive. The gene discussed is ERBB2; the disease is neoplasm.