CA72-4, also known as glycoantigen 72-4, is a tumor marker. This tumor marker is mainly used in clinical practice to assist in the diagnosis of malignant tumors of the digestive system such as gastric cancer. In addition, for malignant tumors of the digestive system such as gastric cancer, this marker can also be applied to monitor the changes of the disease and evaluate the effect of treatment. If it is 3-5 times or higher than the normal value, it is recommended to do abdominal strengthening CT, gastroscopy and colonoscopy to exclude the presence of digestive system malignancies such as gastric cancer. If this index is only mildly increased, it is recommended to monitor this index every 1-3 months, and if necessary, to do enhanced CT abdomen to exclude the presence of malignant tumors.