This kit is used for quantitative detection of carbohydrate antigen 72-4 (CA72-4) in human serum in vitro. Tumor associated antigen 72-4 (CA72-4) is a tumor associated glycoprotein antigen recognized by IgG monoclonal antibody B72.3. The molecular weight of CA72-4 is 48kDa. It has been reported that in many tumor diseases, including gastric cancer, colon cancer, pancreatic cancer and ovarian cancer, the level of CA72-4 in serum and plasma has increased significantly. Especially for gastric cancer and ovarian cancer, it has a high sensitivity and specificity of 95%. CA72-4 level has a good correlation with tumor size and stage. CA72-4 is a good tumor marker for treatment monitoring and follow-up of gastric cancer patients, and has a high diagnostic value with CA19-9 and CEA joint examination.