CEA, or carcinoembryonic antigen, is a broad-spectrum tumor marker, which is associated with a variety of tumors such as colon cancer, pancreatic cancer, gastric cancer, breast cancer and so on. CEA is clinically important for the diagnosis and treatment of malignant diseases and prognosis judgment. A variety of tumors, including colon cancer, pancreatic cancer, gastric cancer, breast cancer, ovarian cancer and so on, can increase the value of CEA significantly, with pancreatic cancer, colon cancer, breast cancer being more sensitive. However, CEA can also be elevated during pregnancy, after drinking a lot of alcohol, or when there is diabetes, colitis, pancreatitis, cirrhosis, etc. Therefore, CEA can only be used as an auxiliary diagnosis of malignant tumors, but not a direct diagnosis of malignant diseases. If CEA is elevated, it is recommended that the next examination be conducted under the guidance of a physician to clarify the cause of the disease.