Breast cancer is a heterogeneous disease, for which treatment strategies depend on its molecular subtypes; for example, endocrine therapy is used for hormone/estrogen-receptor-positive cancer; HER2 targeted therapy is used for human epidermal growth factor receptor 2-positive cancer; chemotherapy; immunotherapy is used for triple-negative breast cancer patients; PARP inhibitors are used for BRCA-mutated triple-negative breast cancer patients [3]. The gene discussed is ERBB2; the disease is breast carcinoma.