The main BC subtypes include: (1) Luminal A, which comprises tumors that overexpress estrogen and/or progesterone hormone receptors (ER and PR, respectively); (2) HER2+, consisting of tumors that overexpress the human epidermal receptor 2 (HER2/neu); (3) Luminal B, which includes tumors that express both hormonal and HER2/neu receptors; and (4) triple-negative breast cancer (TNBC) [3]. This evidence concerns the gene ERBB2 and breast cancer.