Carcinoembryonic antigen (CEA), a glycoprotein produced by colorectal cancer tissue, is a broad-spectrum tumor marker that reflects to people the presence of many kinds of tumors. It is a good tumor marker for judging the efficacy, disease development, monitoring and prognosis estimation of colorectal cancer, breast cancer and lung cancer, but its specificity is not strong, sensitivity is not high, and its role in early diagnosis of tumors is not obvious. What is the clinical significance of CEA test? Normal reference value for carcinoembryonic antigen (CEA): <5.0 μg/L. Carcinoembryonic antigen is widely found in digestive system cancers of endodermal origin, but also in digestive tube tissues of normal embryos, and can be present in trace amounts in normal human serum. Elevated CEA concentrations Elevated CEA is commonly found in colorectal, pancreatic, gastric, breast, and medullary thyroid cancers. But smoking, pregnancy and cardiovascular diseases, diabetes, non-specific colitis and other diseases, serum CEA will also be elevated in 15% to 53% of patients, so CEA is not a specific marker for malignant tumors and has only an auxiliary value in diagnosis. In addition, there is a clear relationship between serum CEA level and the stage of colorectal cancer, the more advanced the lesion, the higher the CEA concentration. 97% of healthy adults have serum CEA concentrations below 2.5 ng/mI. Increased CEA accounts for 45-80% of patients with primary colon cancer. In addition to primary colon cancer, adenopancreatic cancer, bile duct cancer, gastric cancer. Esophageal cancer, adenocarcinoma, lung cancer, breast cancer and tumors of the urinary system also have a high positive rate, generally in the range of 50-70%. CEA is also partially elevated in patients with benign tumors, inflammatory and degenerative diseases, such as colon polyps, ulcerative colitis, pancreatitis and alcoholic cirrhosis, but it is much lower than that of malignant tumors, generally less than 20 μg/L. CEA exceeding 20 ng/ml often indicates the presence of gastrointestinal tumors. Therefore, the determination of CEA can be used as a basis for differential diagnosis between benign and malignant tumors. What should be done when carcinoembryonic antigen is elevated? 1.It is better to take blood test, including CA199, CA724, CA242, CA125 and CA153 for women, if one indicator is found to be elevated, it is time to raise alert. 2, further non-invasive tests can be done, including fecal occult blood and "B" test (including thyroid ultrasound, superficial lymph node examination, etc.), gynecological examination and breast examination is also very necessary. 3, If you have a history of smoking, then a CT lung examination should be performed. 4, Gastroscopy is the next important examination. For women, a mammogram can be done before the gastroscopy, and of course an ultrasound of the breast can be done directly. 5.If all the above results are fine, then further colonoscopy can be considered next, because carcinoembryonic antigen is also found in colon cancer at the earliest. In addition to the above examinations to rule out no problem, there are also the following options: 1. PET-CT examination can be performed, which is equally insensitive to those lesions that cannot be detected by ordinary examinations such as CT, but it may be helpful for more hidden lesions, such as lymph nodes and lesions within the intestinal wall of the stomach wall. 2, CTC is circulating tumor cells. For those who have persistently elevated CEA and all other tests are negative, you can try to perform cutting-edge CTC test, once suspicious tumor cells are found in peripheral blood, then the cell source can be further traced.