ERBB2 and breast carcinoma: Based on the expression of hormone receptors (estrogen and progesterone receptors), human epidermal growth factor receptor 2 (HER2), and the Ki-67 proliferation marker, breast carcinomas are further categorized into hormone-receptor (HR) positive (the Luminal A- and B-like), HER2-positive, and triple-negative breast cancer (TNBC) subtypes [3].