Tumor markers are chemical substances that reflect the presence of a tumor. They either do not exist in normal adult tissues but are only found in embryonic tissues, or their content in tumor tissues greatly exceeds that in normal tissues. Their existence or quantitative changes can suggest the nature of the tumor, which can be used to understand the histogenesis, cell differentiation and cell function of the tumor, and help in the diagnosis, classification, prognosis, and therapeutic guidance of the tumor. Yan Speed, Department of Surgical Oncology, Affiliated Hospital of Qinghai University Tumor markers can be divided into two categories 1) those produced by tumor tissues, including: differentiation antigens; embryonic antigens (AFP, CEA); isoenzymes (NSE); hormones (HCG); tissue-specific antigens (PSA, free PSA); mucins, glycoproteins, glycolipids (CA125); oncogenes and their products; and polyamines 2) those produced by interaction of tumors with their host, including: serum iron, serum iron, serum iron, serum iron and serum iron. 2) Produced by tumor-host interactions, including: serum ferritin; immune complexes; acute phase proteins; interleukin receptors; tumor necrosis factor, etc. Glycoconjugate antigen system overview In the 1980s, experts used hybridoma technology to obtain a large molecule glycoprotein antigen (carbohydrate antigen, CA) that can recognize the specificity of tumors and developed a monoclonal antibody recognition system. CA is a tumor cell-associated antigen. Commonly used CA series include: CA 125 (ovarian cancer-related antigen); CA 19-9 (pancreatic and intestinal cancer-related antigen); CA 15-3 (breast cancer-related antigen); CA 724 (gastric cancer antigen); CA 724 (gastric cancer antigen); CA 724 (gastric cancer antigen); CA 724 (gastric cancer antigen). CA724 (gastric cancer antigen) is a non-specific tumor marker for the detection of gastric cancer and various digestive tract cancers. Elevation of this indicator does not necessarily mean that the patient has a tumor, which is mainly seen in gastrointestinal and ovarian tumors, and it is more sensitive to gastric cancer, mucinous cystic adenocarcinoma of the ovary and non-small-cell lung cancer, and also has a certain degree of sensitivity to the biliary tract system tumors, colorectal cancer, pancreatic cancer, and so on. CA72-4 is a mucin-like high molecular weight glycoprotein recognized by cc49 and B72.3 monoclonal antibodies, with a content of <6 U/mL in normal human serum, and abnormally elevated in various digestive tract tumors and ovarian cancer. The specificity of the test for gastric cancer is high, with >6 U/mL as the critical value. CA72-4 is only elevated in <1% of benign gastric diseases, while the proportion of elevated gastric cancer can reach 42.6%, and the positive rate can reach 56% if detected with CA19-9 at the same time.