CEACAM5 and breast cancer: In breast cancer, the most widely used biomarkers include HER2 (Human epidermal growth factor receptor 2), BRCA1 and BRCA2 (Breast cancer type 1 and 2 susceptibility proteins), CEA (Carcinoembryonic antigen), MUC1 (Mucin 1), VEGF (Vascular endothelial growth factor), CA15-3 (Cancer antigen 15-3), microRNA (miRNAs) [49].