Screening of tumor markers in the clinic is of great significance for tumor diagnosis, treatment efficacy, recurrence monitoring, and disease prognosis. Tumor markers are synthesized and released by tumor cells or produced and released by the body in response to certain tumor cells. They include proteins, enzymes, hormones, sugars and so on. Different elevated tumor markers in the clinic can reflect different diseases. Common tumor markers include alpha-fetoprotein, carcinoembryonic antigen, prostate-specific antigen, glycocalyx antigen 199, cancer antigen 125, neuron-specific enolase and so on. 1. Alpha-fetoprotein (AFP): elevated in primary liver cancer, embryonal tumors of the gonads, gastric or pancreatic cancer. 2. Carcinoembryonic antigen (CEA): elevated in pancreatic cancer, colon cancer, lung cancer, gastric cancer, breast cancer. 3. Prostate-specific antigen: elevated in prostate cancer. 4. Glycosylated antigen 199 (CA199): elevated in pancreatic cancer, gastrointestinal cancer, biliary tract tumors. 5. Carcinoma antigen 125 (CA125): elevated in ovarian cancer, breast cancer, cervical cancer, pancreatic cancer, liver cancer. 6. Neuron-specific enolase: elevated in small cell lung cancer, neuroblastoma.