Moreover, breast cancer is a heterogeneous disease that can be divided into three broad groups: hormone receptor (HR) positive tumors based on estrogen and/or progesterone receptor (ER, PgR) status; human epidermal growth factor receptor 2 (HER2) positive tumors; or triple-negative breast cancers (TNBC). This evidence concerns the gene ERBB2 and triple-negative breast carcinoma.