Based on the presence or absence of molecular markers for estrogen or progesterone receptors and human epidermal growth factor 2 (ERBB2; formerly HER2), BC is divided into three subtypes: hormone receptor-positive/ERBB2 negative (70% of patients), ERBB2 positive (15-20%), and triple-negative (tumors lacking all three standard molecular markers; 15%) [5]. Here, ERBB2 is linked to breast cancer.