Some friends are very nervous when they find their serum CEA (carcinoembryonic antigen) is elevated, and they are even prompted by the physical examination report to “recommend further examination at a higher level hospital” or “pay attention to the review”. “, which scares them half to death! Some people even suspect that they have cancer and have trouble sleeping and eating. Some even suspect that they are suffering from cancer and have trouble sleeping and eating, asking their doctors whether they are suffering from cancer and whether they need to be hospitalized. So what exactly is the problem of elevated CEA in serum? First of all, we need to understand the knowledge about tumor markers. Tumor markers are tumor-related chemical substances produced by tumor cells, and their levels reflect the presence of certain tumors. It is found in the blood, body fluids and tissues of certain tumor patients. Tumor markers were discovered in 1978. Later, several types of tumor markers with clinical significance were discovered one after another. (1) carcinoembryonic proteins: such as alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA); (2) tumor-associated antigens: such as CA19-9, CA125; (3) enzymes: such as lactate dehydrogenase (LDH), neuron-specific enolase (NSE), prostatic acid phosphatase (PAP); (4) specific plasma proteins: such as β2-macroglobulin, periplasmic protein; (5) hormones: such as calcitonin, chorionic gland gonadotropin (HCG), adrenocorticotropic hormone (ACTH). The clinical significance of detecting tumor markers is to use the characteristics of cancer cells in various types of tissues in the body to produce relevant tumor markers to screen for tumors in order to determine the treatment plan. Among these tumor markers, carcinoembryonic antigen (CEA) has a higher specificity (i.e., specificity), so its detection is of great clinical significance. Carcinoembryonic antigen (CEA) is an acidic glycoprotein with a human embryonic antigen determinant cluster, containing 45% to 55% carbohydrates, with a molecular weight of 150-300 kDa, and is a single polypeptide chain consisting of 641 amino acids with a lysine site at the N-terminus. Later studies found that many normal tissues also secrete CEA, such as bronchi, salivary glands, small intestine, bile duct, pancreatic duct, urethra and prostate. However, the colonic mucosa cells of adults secrete the most CEA, about 70 mg per day, which is excreted in the feces, and a small amount is reabsorbed back into the blood. Although CEA has a high specificity, it is not an exclusive marker specific to a certain type of tumor. However, its general direction is malignant tumors of cavernous organs, such as tumors of the gastrointestinal tract, respiratory tract, and urinary tract. For example, about 70% of rectal cancer, 55% of pancreatic cancer, 50% of gastric cancer, 45% of lung cancer, 40% of breast cancer, 40% of urothelial cancer, 25% of ovarian cancer, cholangiocarcinoma and thyroid cancer patients can have elevated carcinoembryonic antigen (CEA). Clinical significance of CEA detection: 1. For screening of malignant tumors: Since the CEA index is almost always high in adenocarcinoma of the cavernous organs, it is especially significant for the diagnosis of colorectal cancer, breast cancer and lung cancer. In general, the more advanced the cancer is and the longer the size of the cancer mass, the higher the CEA; for those with metastasis, the CEA level is often higher than that of those without metastasis; once the CEA is elevated, we should be alert, the normal level is 5, if it is elevated 3 times or more, the possibility of adenocarcinoma is high. If you cannot find the primary lesion, it is recommended to do PET-CT of the whole body to further find the lesion and make a clear diagnosis. 2. On the contrary, if there is not much decrease after surgery, it means that the surgery is not complete and there are residual lesions. If chemotherapeutic drugs are effective, CEA will decrease; on the contrary, if they are ineffective, CEA will continue not to decrease. 3. Assess whether there is tumor recurrence and its disease development: If CEA increases from normal level to abnormal level after surgery or chemotherapy, it means tumor recurrence. If CEA continues to rise gradually, it indicates that there is a progression of the disease and predicts a poor prognosis. It is a better tumor marker for monitoring the presence or absence of recurrence and prognosis assessment. So is any elevated CEA a sign of cancer? Not necessarily! Because CEA is a broad-spectrum tumor marker, its increase often does not represent the presence of a particular tumor, but rather the occurrence of multiple tumors may cause its elevation. It is not an exclusive marker specific to certain tumors. That is, its accuracy and specificity are not 100%! There are many factors that can affect the CEA test. For example: 1) non-neoplastic diseases: patients with various acute and chronic inflammatory diseases, cardiovascular diseases, diabetes, colon polyps, ulcerative colitis, diverticulitis, lung infections, pancreatitis, alcoholic cirrhosis, etc., their serum CEA can also be elevated, but generally less than 20 μg/L. 2) CEA levels in smokers and pregnant women can also be higher than normal. So, you don’t have to worry too much after finding an elevated CEA! So what about normal people with elevated CEA tests? ～The CEA level is not only important, but it should also be defied. 1. Be sure to review it! If the CEA is still high, you need to do imaging or even whole-body PET-CT. 2. If the CEA is high and no lesions are found on imaging, relax and follow up closely. Most guidelines recommend CEA testing every 3-6 months. 3. If the CEA is high on recheck, it is best to be hospitalized.