Carcinoembryonic antigen (CEA) is a broad-spectrum tumor marker with normal values ranging from 0 to 5 μg/L. Carcinoembryonic antigen levels of 220 μg/L can be seen in some malignant tumors as well as in some benign diseases. Carcinoembryonic antigen (CEA) is a tumor marker, which belongs to non-organ-specific tumor-associated antigen. Tumor cells secreting carcinoembryonic antigen are mostly located in luminal organs, such as digestive, respiratory, and urinary tracts, etc. Significantly elevated serum carcinoembryonic antigen can be seen in colon, rectal, gastric, and lung cancers, etc. However, the specificity of carcinoembryonic antigen is very low. However, carcinoembryonic antigen has poor specificity and lacks early diagnostic value, so it is mostly used to assess tumor load or monitor metastatic recurrence. In addition to malignant tumors, elevated carcinoembryonic antigen can also be seen in benign diseases, such as colitis, pancreatitis, and cirrhosis of the liver. Therefore, elevated carcinoembryonic antigen alone cannot diagnose malignant tumors, but should be combined with imaging, endoscopy and pathology. It is recommended to consult a professional doctor for further diagnosis after completing relevant examinations such as gastroenteroscopy and CT of chest and abdomen.