It is well known that breast cancer, which harbors high biological heterogeneity both between and within tumors, is not a single disease and can be classified into four subtypes according to the molecular types, such as luminal A, luminal B, Her2-overexpressed, and triple-negative breast cancer (TNBC) (Perou et al., 2000). The gene discussed is ERBB2; the disease is breast carcinoma.