What are tumor markers? Tumor markers are chemical and biological substances that reflect the presence of tumors. They are either not found in normal adult tissues but only in embryonic tissues, or their content in tumor tissues is much higher than that in normal tissues. Their existence or quantitative change can suggest the nature of tumor, and help to understand the tumor histogenesis, cell differentiation and cell function, so as to help the diagnosis, classification, prognosis judgment and treatment guidance of tumor. Basic classification of tumor markers 1.Tumor tissue production, including: differentiation antigen; embryonic antigen (AFP,CEA); isoenzyme (NSE); hormone (HCG); tissue-specific antigen (PSA,free PSA); mucin, glycoprotein, glycolipid (CA125); oncogene and its products; polyamines, etc. 2.Produced by the interaction between tumor and host, including: serum ferritin; immune complexes; acute temporal proteins; isoenzymes; interleukin receptors; tumor necrosis factor, etc. 3.Some SNPs and miRNAs that are closely related to tumorigenesis, etc. The significance of tumor marker test 1.tumor screening Tumor screening is to find suspicious people from asymptomatic people. Tumor marker test is an effective method for initial screening of tumors. AFP: screening for primary liver cancer, PSA: screening for prostate cancer in men over 50 years old. A125+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 continues to increase, the diagnosis should be confirmed in time. 2. Diagnosis (1) Adjuvant diagnosis: the specificity of tumor markers is not strong enough, so the diagnosis of tumor cannot be confirmed solely based on tumor markers, but it can provide clues for further diagnosis. (2) Differential diagnosis: Ben-Hur protein, AFP, HCG, PSA, etc. have characteristic cancer spectrum. (3) No localized diagnosis: tumor markers lack tissue and organ specificity. (4) Dynamic observation: progressive elevation of tumor markers has clear diagnostic significance; the elevation of markers in benign diseases is transient; (5) the elevation of markers in malignant tumors is persistent. The most important clinical application of tumor markers is to monitor the efficacy and recurrence of metastasis. After surgery, chemotherapy or radiotherapy, there is a good correlation between the rise and fall of specific tumor markers and the efficacy of treatment, which can reflect the recurrence and metastasis of tumor through dynamic observation.