Many of these biomarkers, including mucins, oncofetal proteins such as carcinoembryonic antigen (CEA), oncoproteins such as receptor tyrosine-protein kinase cellular tumor antigen (p53), and cytokeratins such as tissue polypeptide antigen (TPA) and tissue polypeptide specific antigen (TPS), have been recommended for breast cancer. Here, CEACAM5 is linked to breast cancer.