1. What is a tumor? The term tumor is defined in medical monographs as follows: “Tumor is a new organism produced by the cells of human organs and tissues under the long-term action of external and internal harmful factors, which is mainly characterized by excessive cell proliferation. This new organism has nothing to do with the physiological needs of the affected organ, does not grow according to the law of normal organs, loses the function of normal cells, destroys the original organ structure, and some of them can be transferred to other parts of the body and endanger life.” Tumors can be divided into two categories: benign and malignant tumors． And cancer is a kind of malignant tumor. 2.What are the factors of tumor occurrence? Factors affecting tumorigenesis include in vivo factors and in vitro factors. In vitro factors are: physical factors (such as exposure to ionizing radiation can increase the incidence of tumors, etc.), chemical factors (such as dye factory workers exposed to a large amount of aniline can lead to bladder cancer, watch factory workers due to the absorption of fluorescent radioactive material radium and thorium and osteosarcoma, etc.), biological factors (leukemia, lymphoma, and sarcoma in animals and human T-cell leukemia are related to viral infections), and so on. The main factors in the body are: genetic factors. In vivo factors mainly include: genetic factors (a few tumors such as retinoblastoma, nephroblastoma, neuroblastoma of adrenal gland or ganglion have obvious heredity), gender factors (cancers of the reproductive system, breast, thyroid gland and gallbladder are mostly seen in females, while cancers of the lung, esophagus, stomach, liver and nasopharynx are most common in males), and age factors (cancers are most common in people over 40 years of age, sarcomas are most common in young people, and retinal cancer, lymphomas, and T-cell leukemia in humans are all related to viral infections). (cancer is more common in people over 40 years old, sarcoma is more common in young people, retinoblastoma, nephroblastoma, neuroblastoma is more common in young children), and immune status of the organism (tumors often occur in immune-suppressed or immune-tolerant hosts), and so on. 3.What are tumor markers? Tumor marker (TM) is a specific substance that exists or is secreted by tumor cells themselves, with the following characteristics: it is produced by tumor cells and can be measured in blood, tissue fluid, secretion fluid or tumor tissue; the tumor marker of a certain tumor should be detected in most of the patients with that tumor; it is best to be measured before there is any clinical evidence of tumor; the amount of the tumor marker should reflect the tumor; the amount of the tumor marker should reflect the tumor; the amount of the tumor marker should reflect the tumor; and the amount of the tumor marker should reflect the tumor. The amount of tumor marker should be able to reflect the size of the tumor; and to a certain extent, it can help to estimate the treatment effect and predict the recurrence and metastasis of the tumor. Ideal tumor markers should meet these characteristics. However, there is no absolute ideal tumor marker. Most of the known tumor markers exist not only in malignant tumors, but also in benign tumors, embryonic tissues, and even normal tissues. Therefore, these tumor markers are not specific for malignant tumors, but are significantly more prevalent in patients with malignant tumors. Therefore, some people call tumor markers as tumor-associated antigen. 4.What are the tumor markers? At present, there is no tumor marker with strong specificity, and there are more than l0 kinds of tumor markers that have been found and applied to clinical test. Tumor markers can be divided into the following categories: tumor embryonic antigens, such as alpha-fetoprotein, carcinoembryonic antigen; tumor-associated antigens, such as CAl25, CAl5-3, CAl9-9; enzymes and isoenzymes, such as neuron specific enolase, prostate acid phosphatase; oncogenes and oncogenes protein products, such as Cmyc, ras, p53, Rb; plasma proteins such as β2- macroglobulin; hormones, such as sexually transmitted diseases; and oncoprotein products, such as β2- macroglobulin. macroglobulin; hormones, such as sex hormones, thyroid hormones, calcitonin; cellular metabolites, such as lipid-associated salivary acids; trace elements, such as arsenic, copper, iron, selenium, zinc. Note: Different instruments and methods are used in different hospitals, and the reference value of each index may be different, please refer to the report card of each hospital for details. 5. What is the clinical significance of carcinoembryonic antigen (CEA)? Carcinoembryonic antigen (CEA) was firstly discovered by Gold and Freedman in 1965 from fetal and colon cancer tissues. The molecular mass is 22ku of a polysaccharide-protein complex and 45% protein. Generally, CEA is synthesized by fetal gastrointestinal epithelial tissue, pancreas, and hepatocytes.CEA is a non-organ specific tumor-associated antigen, and most of the tumors that secrete CEA are located in the cavernous organs, such as the gastrointestinal, respiratory, and urinary tracts. Elevated serum CEA is mainly seen in colon cancer, rectal cancer, pancreatic cancer, gastric cancer, hepatocellular carcinoma, lung cancer, breast cancer, and other malignant tumors with different degrees of positivity. Intestinal diverticula, rectal polyps, colitis, cirrhosis, hepatitis, and lung disease CEA is also elevated to varying degrees, but with lower positivity rates. 98% of non-smokers have CEA <5ug>5ug/L. Mild elevations can also be seen in renal function abnormalities. CEA can be used to observe the efficacy and prognosis of malignant tumors after surgery, and can also be used to observe the efficacy of chemotherapy patients. 6.What is the clinical significance of alpha-fetoprotein (AFP)? Discovered by Bergstrandh and Czar in 1956 in human fetal serum, AFP is a glycoprotein with a single multimeric peptide chain that swims in the alpha-globin region in an electric field. The molecular mass averages 70 ku and contains 4% sugar. Serum concentrations of AFP are often markedly elevated in patients with primary hepatocellular carcinoma, but in some patients AFP is not elevated. In patients with viral hepatitis and cirrhosis, the concentration of AFP is elevated to different degrees, and the reason for the elevation is mainly due to the regeneration of damaged hepatocytes and infantilization, the hepatocytes regain the ability to produce AFP, and with the repair of the damaged hepatocytes, the AFP can be restored to normal gradually. The concentration of AFP in serum of patients with embryonic tumors of the reproductive glands can also be seen to be elevated, such as testicular cancer, teratoma and so on. After the third month of pregnancy, serum AFP concentration begins to rise, and reaches the peak at 7-8 months. Abnormal elevation of AFP in serum of pregnant women should be considered the possibility of fetal neural tube defect malformation. 7, What is the clinical significance of cancerantigen 125 (cancerantigen l25, CAl25)7 Detected from epithelial ovarian cancer antigen by Bast et al. A glycoprotein that can be bound by the monoclonal antibody OAl25. Molecular mass is 20 Dku. Serum levels of CAl25 are markedly elevated in patients with ovarian cancer. Levels decline rapidly in the later stages of surgery and chemotherapy. When recurrence occurs, an increase in CAl25 can be presented several months prior to clinical diagnosis, and serum CAl25 is especially markedly higher than normal reference values in patients with ovarian cancer metastases. Other non-ovarian malignant tumors also have a certain positive rate, such as breast cancer, pancreatic cancer, gastric cancer, lung cancer, colorectal cancer and other gynecological tumors. Non-malignant tumors, such as endometriosis, pelvic inflammatory disease, ovarian cysts, pancreatitis, hepatitis, cirrhosis and other diseases are also elevated to varying degrees, but the positive rate is low, and care should be taken to differentiate them during diagnosis. In many benign and malignant pleural and peritoneal fluid, CAl25 is found to be elevated, and a higher concentration of CAl25 can also be detected in amniotic fluid. cAl25 may also be elevated in the first 3 months of early pregnancy. 8.What is the clinical significance of cancer antigen l5-3 (CAl5-3)? It is named by Hilkens et al. from human breast fat globules and Kufu et al. from liver metastasis of breast cancer cell membrane made of monoclonal antibody combined into one.CAl5-3 molecular mass is 400ku.CAl5-3 exists in many kinds of adenocarcinomas, such as breast cancer, lung adenocarcinomas and ovarian cancers etc.CAl5-3 can be used as the primary cancer, and can be used as the primary cancer. CAl5-3 can be used as an auxiliary diagnostic indicator for primary breast cancer, and also as an indicator for monitoring tumor recurrence and metastasis during post-surgical follow-up. Other malignant tumors, such as lung cancer, kidney cancer, colon cancer, pancreatic cancer, ovarian cancer, uterine cervix cancer, primary liver cancer, etc. also have different degrees of positive rate. 9. What is the clinical significance of carbohydrate antigen l9-9 (CAl9-9)? By Koprowski equal to l979 with colon cancer cells immunization mice, and hybridization with myeloma obtained Ii6NSl9-9 monoclonal antibody. It is a glycan antigen with a molecular mass of 5000 ku, and its structure is a combination of Lea antigenic substance and Lexa salivary acid. The level of serum CAl 9-9 is obviously elevated in patients with pancreatic cancer, gallbladder cancer and bile duct jugular cancer, especially in patients with advanced pancreatic cancer, the concentration of serum CAl9-9 can reach 400,000kU/L, which is an important auxiliary diagnostic index. Gastric cancer, colon cancer, hepatocellular carcinoma, acute pancreatitis, cholecystitis, cholestatic cholangitis, cirrhosis, hepatitis and other diseases, CAl9-9 is also elevated to varying degrees, and should be distinguished. It is also elevated in breast cancer and lung cancer. 10.What is the clinical significance of carbohydrate antigen 242 (CA242)? CA242 is a marker related to mucin and a sialylated glycolipid antigen. CA242 is a new tumor antigen that is elevated when tumors develop in the GI tract. It helps in the diagnosis of liver, stomach, colon and pancreatic cancer. It is superior to CAl99 for the diagnosis of pancreatic cancer, but this marker is not indicated for the diagnosis of squamous cell carcinoma.