ERBB2 and breast cancer: According to the expression of the hormone receptors [estrogen (ER+), progesterone (PR+), and human epidermal growth factor receptor 2 (HER2 +)], BC is subclassified into five types: luminal A, luminal B, normal-like, HER2-enriched, “basal-like,” or triple-negative subtypes (TNBC) (Vuong et al., 2014).