At present, the serum tumor markers of breast cancer are mainly with carcinoembryonic antigen (carcinoma-embryonic antigen, CEA), carbohydrate antigen 15-3 (cancer antigen15-3, CA15-3), carbohydrate antigen-125 (cancer antigen-125, CA-125) and tissue polypeptide specific antigen (tissue polypeptide-specific antigen, TPS) etc. [16]. The gene discussed is CEACAM5; the disease is breast cancer.