ERBB2 and breast cancer: Serum carcinoma oncomarkers in BC include carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 125 (CA-125), CA15-3, CA27-29, HER2, epidermal growth factor receptor (EGFR), a cluster of differentiation 44 (CD 44), epithelial cell adhesion molecule (EpCAM, CD326), Ki-67, tissue polypeptide-specific and tissue polypeptide antigen [59].