Carcinoembryonic antigen (CEA) and carbohydrate antigens (CAs) such as CA 15-3, CA 15-5, CA 19-9, CA27, CA 29, and CA 125 have been evaluated for therapy monitoring in breast cancer (BC) patients, as well as compared directly with the monitoring value of other blood analytes [91]. This evidence concerns the gene CEACAM5 and breast carcinoma.