With the change of lifestyle and living environment, the incidence and mortality rate of various malignant tumors are significantly higher nowadays, which makes many people afraid of talking about “cancer”. In fact, tumor has gradually changed from a terminal disease in the past to a “chronic disease”. Although the risk of death is still not negligible, through early diagnosis and standardized treatment, more and more patients are able to survive for a longer period of time and even achieve “cure”. Of course, to win the best prognosis, “early” is still a prerequisite, and one of the easiest ways to do this is to get tested – tumor markers. Tumor markers are an extremely simple and effective tumor screening method for the general population. Because for the examinee, only a simple blood draw is needed to perform it, and at the same time it can play a very good screening effect. 1.What is tumor marker? Tumor markers, also known as tumor markers, are substances that are characteristically present in malignant tumor cells, or produced abnormally by malignant tumor cells, or produced by the host in response to tumor stimulation. Tumor markers first started in 1846, and nowadays they are mainly divided into 7 categories. Their uses can not only perform early detection of tumors and tumor screening, but also assist in the diagnosis, differential diagnosis and staging of tumors, detection of tumor efficacy, indicators of tumor recurrence, and prognosis of tumors. It can be said that it can not only help you to detect tumor early, but also help you to evaluate the effect of tumor treatment, prevent and detect tumor recurrence early, etc. 2.What is the correlation between tumor markers and cancer? So far, hundreds of tumor markers have been discovered successively, but only 20 or so of them can be successfully applied to clinical diagnosis and treatment of tumors. It is necessary for us to understand their specific meanings a little. (1) Carcinoembryonic antigen (CEA) Carcinoembryonic antigen is a glycoprotein embryonic antigen found in fetal and colon cancer tissues, which is a broad-spectrum tumor marker. the positive rate of CEA in malignant tumors is colon cancer (70%), gastric cancer (60%), pancreatic cancer (55%), lung cancer (50%), breast cancer (40%), ovarian cancer (30%), and uterine cancer (30%). There are more false positives in smokers, and elevated serum CEA occurs in about 15% to 53% of women during pregnancy and in patients with cardiovascular disease, diabetes mellitus, and nonspecific colitis. (2) Alpha-fetoprotein (AFP) AFP is the best marker for the diagnosis of primary liver cancer, with a positive diagnostic rate of 60% to 70%. If serum AFP > 400 μg/L for 4 weeks or 200-400 μg/L for 8 weeks, the diagnosis of primary hepatocellular carcinoma can be made in combination with imaging examination. In addition, it is also mostly seen in germ cell carcinoma, ovarian tumor, gastric cancer, bile duct cancer, pancreatic cancer, etc. Some benign diseases (such as hepatitis, cirrhosis, enteritis, and hereditary tyrosinemia) may also be elevated; it may also show a transient increase in pregnancy. (3) α-L-amylosidase (AFU) α-L-amylosidase (AFU) is a lysosomal acid hydrolase that catalyzes the hydrolysis of biologically active macromolecules such as glycoproteins and glycolipids that contain a rock sugar base. It is now considered a new tumor marker for primary liver cancer due to the significant elevation of AFU in patients with hepatocellular carcinoma. Dynamic observation is important for judging the efficacy, prognosis and recurrence of hepatocellular carcinoma. In addition, serum AFU can also be increased in patients with metastatic liver cancer, lung cancer, breast cancer, ovarian cancer, and uterine cancer; there is also a mild increase in serum AFU in cirrhosis, chronic hepatitis, and gastrointestinal bleeding. (4) Glycoantigen 19-9 (CA19-9) CA19-9 is a glycoantigen associated with gastrointestinal cancer and is usually found in normal fetal pancreas, gallbladder, liver, intestine and normal adult pancreatic and bile duct epithelium. Detection of patient’s serum CA19-9 can be used as an auxiliary diagnostic indicator for malignant tumors such as pancreatic cancer, gastric cancer, colorectal cancer, bile duct cancer and gallbladder cancer, and is also of great significance in monitoring changes and recurrence of disease. In addition, many patients with benign diseases of the digestive system also have elevated serum CA19-9. It has been reported that nearly 10% of patients with pancreatitis have moderately elevated serum CA19-9. (5) Cancer antigen 15-3 (CA15-3) CA15-3 can be used as a preferred indicator for breast cancer diagnosis and treatment, postoperative follow-up and metastatic recurrence. It has low sensitivity (60%) for early stage breast cancer, 80% sensitivity for advanced stage, and high positivity rate (80%) for metastatic breast cancer. In addition, serum CA15-3 can also be increased in lung, ovarian, lung and colorectal cancers. Serum CA15-3 is also elevated in patients with certain benign breast disorders, endometriosis, and ovarian cysts. (6) Glycoantigen 72-4 (CA72-4) CA72-4 is one of the best tumor markers for the diagnosis of gastric cancer, with high specificity and sensitivity of 28% to 80%. In addition, serum CA72-4 may also be elevated to varying degrees in patients with other gastrointestinal cancers, breast cancer, lung cancer, ovarian cancer and other diseases. Certain benign gastrointestinal diseases may also have mild elevation of serum CA72-4. (7) Cancer antigen 125 (CA125) CA125 is present in epithelial ovarian cancer tissues and patient serum and is the most studied ovarian cancer marker, which is important in early screening, diagnosis, treatment and prognosis application studies. the sensitivity of CA125 for epithelial ovarian cancer can reach about 70%. In addition, it is also seen in lung cancer, pancreatic cancer, breast cancer, liver cancer, gastrointestinal malignancy, uterine cancer, etc. Women with pelvic inflammatory disease, endometriosis, menstruation, ovarian cysts, uterine fibroids, chronic hepatitis, pancreatitis, cholecystitis, and pneumonia also have elevated serum CA125. (8) Prostate-specific antigen (PSA) PSA is a glycoprotein synthesized by human prostate epithelial cells and secreted into seminal plasma. PSA is mainly found in prostate tissue and does not exist in women, and the level of PSA in normal male serum is very low, with a serum reference value of <4 μg/L; PSA is organ-specific, but not tumor-specific. The positive rate for the diagnosis of prostate cancer is 80%. Benign prostate diseases (e.g. prostatitis, prostatic hyperplasia) can also cause elevated serum PSA. (9) β2 microglobulin (β2-MG) β2 microglobulin is an endogenous, low molecular weight serum protein secreted by lymphocytes and most other nucleated cells. It is present in urine, plasma, brain crest fluid and on the surface of lymphocytes, multinucleated neutrophils and platelets in very small amounts. It is mostly used clinically to diagnose lymphoproliferative disorders such as leukemia, lymphoma and multiple myeloma. Some diseases such as hepatitis, nephritis, rheumatoid arthritis, and immune diseases may also have elevated serum β2-MG. (10) Neuron-specific enolase (NSE) NSE is a tumor marker for small cell lung cancer with a positive diagnostic rate of 91%. It helps in the differential diagnosis of small cell lung cancer and non-small cell lung cancer. It is also valuable for the observation of the efficacy and recurrence monitoring of small cell lung cancer. In neuroblastoma, serum NSE concentration can be significantly increased in neuroendocrine cell tumors. In addition, if hemolysis occurs or if there is prolonged post-collection stagnation in separating plasma serum or improper centrifugation that destroys cells, it can lead to elevated NSE. (11) Cytokeratin 19 (Cyfra21-1) Cyfra21-1 is the preferred marker for non-small cell lung cancer, especially squamous lung cancer. Combined testing with CEA and NSE is valuable for differential diagnosis of lung cancer and monitoring of the disease. In addition, cervical cancer, esophageal cancer, bladder cancer, nasopharyngeal cancer, ovarian cancer, and gastrointestinal cancer also have elevated serum Cyfra21-1. Hepatitis, pancreatitis, pneumonia, prostate enlargement and other diseases can also have some elevation of serum Cyfra21-1. (12) Squamous cell carcinoma antigen (SCC) Squamous epithelial cell carcinoma antigen (SCC) is a subtype of the tumor-associated antigen TA-4, a glycoprotein. SCC is present in the cytoplasm of squamous epithelial cell carcinomas of the uterus, cervix, lung, head and neck, and is especially abundant in the cells of non-keratinizing carcinomas. Elevated levels of SCC in serum are seen in 83% of cervical cancer, 25%-75% of squamous cell carcinoma of lung, 30% of stage I esophageal cancer, 89% of stage III esophageal cancer; also seen in ovarian cancer, uterine cancer and squamous epithelial cell carcinoma of neck. It is often used clinically to monitor the effectiveness of treatment, recurrence, metastasis or to evaluate the prognosis of the above malignancies. Certain benign diseases including lung infection, skin disease, kidney failure and liver disease may also show elevated serum SCC. 3.How to treat elevated tumor markers correctly? Currently, many health checkup packages include the option of "tumor markers". When tumor markers are found to exceed the normal value in the physical examination report, many people will fall into the panic of "cancer". Do elevated tumor markers mean cancer? What conditions should be taken seriously? In fact, there is not a one-to-one relationship between tumor markers and cancer. If only one or two tumor markers are elevated and there are no symptoms, it does not mean that you have cancer. Tumor markers are only an indicator for tumor screening and post-operative monitoring of tumors, and it cannot be used for cancer diagnosis alone. In addition to tumor markers, it needs to be combined with clinical symptoms, physical signs and imaging to make a comprehensive judgment in diagnosing cancer. For some people who are found to have elevated tumor markers, if there are no obvious symptoms and no masses are found in imaging, it is generally recommended to review or dynamic observation after 1 month. If the psychological burden is high, you can go directly to other hospitals of higher level or the same level for direct review. As various factors such as blood sampling and machine precision can affect the index. If the tumor markers are much higher than the normal value and persistently elevated, we should be highly alert and further screening for cancer elimination should be performed.