ERBB2 and breast cancer: Gene markers such as BC type (e.g. BRCA1, BRCA2), and protein-based markers such as osteopontin (OPN), cytokeratin 19 fragment (CIFRA-21-1), carcinoembryonic antigen (CEA), human epidermal growth factor receptor 2 (HER2), vascular endothelial growth factor (VEGF), polypeptide antigen (TPA), and cancer antigen CA 27.29, are the most significant biomarkers found in British Columbia7–9.