CEACAM5 and breast cancer: Extensive searches have revealed several breast cancer-specific markers: MUC-1 family mucin glucoproteins like CA 15.3, BR27.29 (or CA27.29), and mucin-like carcinoma-associated antigen, CA 549, carcinoembryonic antigen (CEA), serum human epidermal growth factor receptor (HER) 2/c-erbB-2, cytokines and cytokeratin fragments [5-10].