According to immunohistochemical evaluation (IHC) of hormone receptors (HR) and human epidermal growth factor receptor 2 (HER2), breast cancer is classified as estrogen (ER) and/or progesterone receptor (PgR) positive (65%), HER2-positive (20%), and triple-negative (TNBC, 15%)3. Here, ERBB2 is linked to breast cancer.