Tumor marker is a kind of substance which is synthesized and secreted by tumor cell gene expression during the process of malignant tumor occurrence and proliferation, or abnormally produced or elevated by the body’s reaction to the tumor, reflecting the existence and growth of the tumor, and it exists in the patient’s blood, body fluids, cells or tissues, and it can be measured by methods of biochemistry, immunology and molecular biology, which has clinical value in the auxiliary diagnosis of the tumor, differential diagnosis, observation of therapeutic efficacy, monitoring of recurrence and prognosis evaluation. It is of clinical value for the auxiliary diagnosis, differential diagnosis, observation of curative effect, monitoring of recurrence and prognosis evaluation of tumors. AFP is a glycoprotein synthesized by liver and yolk sac during embryonic period, and its content in normal adult blood circulation is very small <20μg afp="">400μg/L for 4 weeks or 200~400μg/L for 8 weeks, combined with the imaging examination, it can be used to make the diagnosis of primary hepatocellular carcinoma. The concentration of AFP in serum of patients with acute and chronic hepatitis and cirrhosis can be elevated to different degrees, and its level is often <300ug/L. Reproductive embryonic tumors (testicular cancer, teratoma) can be seen to have elevated levels of AFP. Carcinoembryonic antigen (CEA) is a glycoprotein embryonic antigen found in fetal and colon cancer tissues, which belongs to broad-spectrum tumor markers. The normal reference value of serum CEA is <5μg/L. The positive rate of CEA in malignant tumors is 70% for colon cancer, 60% for stomach cancer, 55% for pancreatic cancer, 50% for lung cancer, 40% for breast cancer, 30% for ovarian cancer and 30% for uterine cancer. Some benign diseases such as rectal polyps, colitis, liver cirrhosis, lung disease also have different degree of elevated CEA level, but the degree of elevation and the positive rate is low.CEA belongs to adhesion molecule, which is an important sign of metastatic recurrence of many kinds of tumors. 3.Cancer antigen 125 (CA125) CA125 exists in epithelial ovarian cancer tissues and patients' serum, it is the most studied ovarian cancer marker, and is of great significance in the early screening, diagnosis, treatment and prognosis of the application of the study.The sensitivity of CA125 to epithelial cancer of ovary can reach about 70%. The sensitivity of CA125 for ovarian epithelial cancer can reach about 70%. Other non-ovarian malignant tumors (cervical cancer, uterine cancer, endometrial cancer, pancreatic cancer, lung cancer, gastric cancer, colorectal cancer, breast cancer) also have a certain positive rate. Benign gynecological diseases (pelvic inflammatory disease, ovarian cysts, etc.) and early pregnancy may show different degrees of elevated serum CA125 levels. 4.Cancer antigen 15-3 (CA15-3) CA15-3 can be used as an indicator of breast cancer auxiliary diagnosis, postoperative follow-up and metastatic recurrence. The sensitivity of early breast cancer is low (60%), the sensitivity of late stage is 80%, and the positive rate of metastatic breast cancer is high (80%). Other malignant tumors also have a certain positive rate, such as: lung cancer, colon cancer, pancreatic cancer, ovarian cancer, cervical cancer, primary liver cancer and so on. 5.Glycoantigen 19-9 (CA19-9) CA19-9 is a kind of glycoantigen associated with gastrointestinal tract cancer, usually distributed in normal fetal pancreas, gallbladder, liver, intestines and normal adult pancreas, bile duct epithelium and so on. Detecting patients' serum CA19-9 can be used as an auxiliary diagnostic index for pancreatic cancer, gallbladder cancer and other malignant tumors, which is of great significance in monitoring the changes and recurrence of the disease. Serum CA19-9 levels are also elevated to different degrees in patients with gastric cancer, colorectal/rectal cancer, liver cancer, breast cancer, ovarian cancer and lung cancer. Certain digestive tract inflammation CA19-9 also has different degrees of elevation, such as: acute pancreatitis, cholecystitis, cholestatic cholangitis, hepatitis, cirrhosis of the liver and so on. 6.Cancer antigen 50 (CA50) CA50 is a marker for pancreatic and colorectal cancer, and it is the most commonly used glycan antigen tumor marker, because of its wide presence in pancreas, gallbladder, liver, stomach, colorectum, bladder, uterus, and its tumor recognition spectrum is wider than that of CA19-9, therefore, it is a universal tumor marker related antigen, rather than specifically referring to a certain organ's tumor marker.CA50 can be detected in different malignant tumors, and can also be detected in different malignant tumors. CA50 can be detected in many kinds of malignant tumors with different positive rates, the positive detection rate of pancreatic cancer and gallbladder cancer is the highest, accounting for 94.4%; others are hepatocellular carcinoma (88%), ovarian and uterine carcinoma (88%), and malignant pleural fluid (80%), etc. It can be used in pancreatic cancer, gallbladder cancer and other malignant tumors, and can be used in pancreatic cancer, gallbladder cancer and other malignant tumors. It can be used in the early diagnosis of pancreatic cancer, gallbladder cancer and other tumors, and also has high value in the diagnosis of liver cancer, gastric cancer, colorectal cancer and ovarian tumor. 7, Glycolipid antigen 242 (CA242) CA242 is a glycolipid antigen related to pancreatic cancer, gastric cancer and colorectal cancer. Serum CA242 is used for auxiliary diagnosis of pancreatic cancer and colon cancer, with good sensitivity (80%) and specificity (90%). Lung cancer, liver cancer, ovarian cancer patients' serum CA242 content can be seen to be elevated. CA72-4 is one of the best tumor markers for diagnosis of gastric cancer, with high specificity for gastric cancer, its sensitivity can reach 28-80%, and can monitor more than 70% of gastric cancers if it is combined with CA19-9 and CEA. CA72-4 level has obvious correlation with the stage of gastric cancer and generally increases in stage III-IV of gastric cancer, and the positive rate of CA72-4 in gastric cancer with metastasis is much higher than that in non-metastatic patients, and the level of CA72-4 can be rapidly decreased to normal after operation. CA72-4 levels are first elevated in 70% of recurrent cases. The main advantage of CA72-4 over other markers is its high specificity for the differential diagnosis of benign lesions, with a detection rate of only 0.7% in a large number of patients with benign gastric disease. The detection rate is only 0.7% in many patients with benign gastric disease. There is also a certain positive rate for colon/rectal cancer, pancreatic cancer, liver cancer, lung cancer, breast cancer and ovarian cancer. 9, Ferritin (SF) Elevated ferritin can be seen in the following tumors: acute leukemia, Hodgkin's disease, lung cancer, colon cancer, liver cancer and prostate cancer. Detecting ferritin has diagnostic value for liver metastatic tumors, 76% of patients with liver metastases have ferritin level higher than 400μg/L. When liver cancer, AFP measurement is low, the ferritin measurement can be supplemented to improve the diagnostic rate. Ferritin is also elevated in hyperpigmentation, inflammation, and hepatitis. The elevation may be due to cell necrosis, blocked erythropoiesis or increased synthesis in tumor tissue. 10, prostate specific antigen (PSA) PSA is synthesized by human prostate epithelial cells and secreted into the seminal plasma of a glycoprotein, PSA is mainly present in the prostate tissue, female body does not exist, the normal male serum PSA content is very low, the serum reference value of <4 μg psa="" t-psa="">0.25 for benign diseases; F-PSA/T-PSA<0.16 highly suggestive of prostate cancer. 0.16 is highly suggestive of prostate cancer. < p=""> 11. Prostate acid phosphatase (PAP) Elevated serum PAP of prostate cancer is an important indicator for prostate cancer diagnosis, staging, efficacy observation and prognosis. Prostatitis and prostate hyperplasia PAP is also increased to a certain degree. 12, β2-microglobulin (β2-MG) β2-microglobulin (β2-m) is expressed on the surface of most nucleated cells. It is mostly used clinically to diagnose lymphoproliferative diseases, such as leukemia, lymphoma and multiple myeloma. Its level correlates with the number of tumor cells, growth rate, prognosis and disease activity. In addition, this level is used to stage myeloma patients. Serum β2-MG can be elevated in renal failure, inflammation, and a variety of diseases. Therefore, serum β2-MG should be excluded due to certain inflammatory diseases or reduced glomerular filtration function. 13.Neuron specific enolase (NSE) NSE is an isoenzyme of enolase, which is a tumor marker for small cell lung cancer (SCLC), with a positive diagnostic rate of 91%. It is useful in the differential diagnosis of small cell lung cancer and non-small cell lung cancer (NSCLC). It is also valuable for the observation of the efficacy of small cell lung cancer and the monitoring of recurrence. Neuroblastoma, neuroendocrine cell tumor serum NSE concentration can be significantly increased. 14, Cytokeratin 19 (Cyfra21-1) Cyfra21-1 is a soluble fragment of cytokeratin-19, which is the first choice for non-small cell lung cancer, especially squamous lung cancer. Combined with CEA and NSE, Cyfra21-1 is valuable for differential diagnosis and disease monitoring of lung cancer, and it is also a good auxiliary diagnostic and therapeutic monitoring index for breast cancer, bladder cancer and ovarian cancer. 15.Squamous cell carcinoma antigen (SCCA) Squamous cell carcinoma antigen (SCCA) is a tumor-associated antigen TA-4 extracted from squamous epithelial cell carcinoma of the cervix, and the serum content of normal human is very small <2.5 μg/L. SCCA is a tumor marker for squamous carcinoma, which is suitable for the auxiliary diagnosis of cervical cancer, squamous carcinoma of the lungs, esophageal carcinoma, head and neck carcinoma, and bladder carcinoma, as well as for the monitoring of treatment and recurrence. 16.Nuclear Matrix Protein-22 (NMP-22) NMP-22 (Nuclear Matrix Protein-22) is a component of cellular nuclear skeleton. It is closely related to cellular DNA replication, RNA synthesis, gene expression regulation and hormone binding. In bladder cancer, a large number of tumor cells apoptosis and release NMP22 into the urine, and the urinary NMP22 can increase 25 times. The sensitivity of NMP22 in urine is 70% and the specificity is 78.5% with 10kU/mL as the threshold value for the diagnosis of bladder cancer. The sensitivity of diagnosis for invasive bladder cancer is 100%. 17.Alpha-L-fucosidase(AFU) AFU is another sensitive and specific new marker for primary hepatocellular carcinoma. The activity of serum AFU in patients with primary hepatocellular carcinoma is significantly higher than that in other types of diseases (including benign and malignant tumors). The dynamic curve of serum AFU activity is of great significance in determining the therapeutic effect of hepatocellular carcinoma, estimating the prognosis and predicting recurrence, and it is even better than AFP.However, it is worth to be raised that there is some overlap of the determination of serum AFU activity in some metastatic hepatocellular carcinomas, lung carcinomas, breast carcinomas, ovary or uterine carcinomas, and it even has a mildly elevated level in some non-tumor diseases such as cirrhosis of the liver, chronic hepatitis, and gastrointestinal hemorrhage. In addition, AFU should be measured at the same time as AFP when using AFU, which can improve the diagnostic rate of primary liver cancer and have a better complementary effect. Secondly, in order to improve the accuracy and detection rate of tumor markers in clinical diagnosis, we suggest the use of combined detection for some tumors. We summarize them into a table listed below. Cancer is one of the most important culprits of global disease mortality. According to statistics, there are 173 new cancer patients per 100,000 people worldwide, and 110 per 100,000 people in China. Experts point out that 1/3 of all tumors can be prevented, 1/3 of all tumors can be cured and 1/3 of all tumors can prolong life. At present, the diagnosis and treatment of cancer in developed countries are mostly in the early stage, and some tumor markers are taken as mandatory tests for certain people (e.g. PSA, etc.). Therefore, tumor marker (TM) testing is of great significance, which is summarized as follows: I. Tumor Screening Tumor screening is to look for suspicious people from asymptomatic people. Tumor marker test is an effective method for initial screening of tumors. Tumor marker test is an effective method for initial screening of tumors. It is commonly used for screening high-risk groups. AFP: screening for primary liver cancer. PSA: Screening for prostate cancer in men over 50 years old. High-risk HPV :Screening for cervical cancer. CA125+Ultrasound:Screening for ovarian cancer in women over 50 years old. Abnormally elevated tumor markers without obvious symptoms and signs need to be reviewed and followed up. If it is persistently elevated, the diagnosis should be confirmed in time. Diagnosis Auxiliary diagnosis: The specificity of tumor markers is not strong enough to confirm the diagnosis of tumor solely based on tumor markers, but it can provide clues for further diagnosis. Differential diagnosis: Ben-Chou protein, AFP, HCG, PSA, etc. have characteristic cancer spectrum. Cannot localize the diagnosis: tumor markers lack tissue and organ specificity. Dynamic observation: progressive elevation of tumor markers has clear diagnostic significance; elevation of markers in benign diseases is transient; elevation of markers in malignant tumors is persistent. Monitoring the condition and therapeutic effect Monitoring the therapeutic effect and recurrence and metastasis is the most important clinical application of tumor markers. After surgery, chemotherapy or radiotherapy, there is a good correlation between the rise and fall of the content of specific tumor markers and the therapeutic efficacy, and the dynamic observation can reflect whether the tumor has recurrence or metastasis.