CEACAM5 and neoplasm: The tumor markers in serum such as carcinoembryonic antigen (CEA) 4, human chorionic gonadotropin (HCG) 5, prostate-specific antigen (PSA) 6, alpha-fetoprotein (AFP) 7, and cancer antigen-125 (CA-125) 8 are common but of poor accuracy and efficacy, for these proteins sometimes unexpected high in the blood of healthy people.