Tumor markers are substances that are secreted or shed by cancer cells into body fluids or tissues, or produced by patients in response to cancerous cells in their own bodies and enter into body fluids or tissues. Some of these substances are not present in normal human body and are only seen in embryonic period; some are present in normal human body but at weak level and only exceed the normal value when suffering from cancer. Through the testing of tumor markers, it can provide early warning or assist in diagnosis, analyze the course of disease, guide treatment, monitor recurrence or metastasis, and judge prognosis, etc. 1. Alpha-fetoprotein (AFP): It exists in fetal period and decreases after birth. It is <5 micrograms/liter in normal people and increases significantly after hepatocellular carcinoma occurs, and is a common indicator for diagnosing liver cancer. Generally speaking, the positive rate of diagnosing hepatocellular carcinoma can reach 70%~90% when AFP>500 micrograms/liter L, and its specificity is good. 2. Carcinoembryonic antigen (CEA): It exists on the cell surface of embryonic gastrointestinal mucosa epithelial cells and some malignant tissues, and its serum value is <30 μg/L in normal human (the normal value varies in different laboratories). Elevated CEA is mainly seen in colon cancer, but also in pancreatic cancer, breast cancer, lung cancer, thyroid cancer and some non-cancerous patients, therefore, CEA is not significant as a diagnosis, but as a diagnosis that has been clearly After cancer diagnosis and treatment such as surgery, regular testing (once in 2~4 weeks) can help analyze the efficacy of treatment, judge the prognosis, and predict whether recurrence has metastasized or not is valuable. 3.CA19-9: It is a ganglioside without organ specificity and is elevated in many kinds of adenocarcinomas, such as pancreatic, lung, colon and gastric cancers, among which the sensitivity of pancreatic, gastric and bile duct cancers is higher and it is a more reliable marker of pancreatic cancer. CA19-9 measurement helps to judge the prognosis and its prediction of recurrence and metastasis is often found before radiography. CA19-9 and CEA can be combined to identify gallstones and gallbladder cancer, and can also improve the sensitivity and specificity of screening and screening for gastric cancer. 4.CA12-5: Normal fetal and adult ovarian cells do not express CA12-5 antigen, and ovarian cancer epithelial cells are highly sensitive but not highly specific because it is also present in breast, lung, benign and malignant exudate.CA12-5 is associated with tumor recurrence, therefore, it helps to CA12-5 is associated with tumor recurrence, therefore, it helps to follow up the disease, and it is an important reference indicator for second treatment. 5.CA24-2: It is present in normal pancreatic and colonic mucosa, but it is very faint. It is elevated in pancreatic cancer and colon cancer, and the positive rate for the diagnosis of pancreatic cancer is as high as 74%~79%. 6.CA15-3 is an important antigen for monitoring breast cancer and is present in many kinds of adenocarcinoma cells, such as breast, lung, ovarian and pancreatic cancers. It has a higher relevance to breast cancer and is more sensitive and specific to breast cancer than CEA, therefore, it is mainly used to determine the progression and metastasis of breast cancer, monitor treatment and recurrence. 7.Squamous epithelial cell carcinoma antigen (SCC): high specificity but low sensitivity, used to monitor cervical cancer, lung cancer, head and neck epithelial cancer. 8.Prostate specific antigen (PSA): It exists only in the cytoplasm of prostate alveoli and ductal epithelial cells, and is a more specific marker of prostate cancer. It is used to diagnose prostate cancer, identify the source of metastatic adenocarcinoma, and judge the efficacy and prognosis. 9.Human chorionic gonadotropin (HCG): It is a glycoprotein present in the placenta. It is present in trace amounts in normal blood and increases in urine and blood during pregnancy, and is used to monitor the response to treatment and recurrence of non-seminomatous cell tumors, especially in the diagnosis of choriocapillary epithelial carcinoma, and has important value in the observation of efficacy and prediction of prognosis. 10.Neuronal enolase (NSE): It exists in neurons and cells of neural origin, and is a marker for neuronal cell carcinoma and small cell lung cancer, especially for small cell lung cancer, with high specificity and sensitivity, and can be used for diagnosis, differential diagnosis, efficacy and disease assessment. 11.β2-Microglobulin (β2-MG): It is used to diagnose lymphoproliferative diseases such as leukemia, lymphoma and multiple myeloma, and its level is related to the number of tumor cells, growth rate, prognosis and disease activity. 12.Ferritin (SF): It is elevated to different degrees in the blood of many cancer patients, and the positive rate in liver cancer patients answers more than 70%, which can assist in the diagnosis of liver cancer. 13.CA50: It is a non-specific broad-spectrum tumor marker, a sialic acid ester and sialic acid glycoprotein, which generally does not exist in normal tissues. When cells are malignant, glycosylase is activated, causing changes in cell surface glycosyl structure and becoming CA50 marker.