Tumor markers are some special substances produced in the human body, the content of which in tumor patients is significantly higher than that in normal people. Determination of their content by serum or plasma can provide a basis for early diagnosis of cancer, and therefore they are figuratively called wind vane for tumor diagnosis and treatment. Long-term unexplained cough, coughing up blood, suspected lung tumor can choose to test CEA, Cyfra211, NSE, SCC, CA125; stomach pain, vomiting blood, blood in stool, suspected gastrointestinal tumors can choose to test CEA, CA199, CA125, CA724, CA242; liver and gallbladder tumors can choose to test CEA, AFP, CA199; pancreatic tumors can choose to test CEA, CA199, CA122, CEA199, CA199, CEA199, CEA199, CEA199, CEA199, CEA199, CEA199, CA199, CA125 and CA242 for pancreatic tumors; CEA, CA125 and CA153 for breast tumors; SCC and CEA for cervical tumors; CA125, CA153 and CEA for ovarian tumors; and PSA for prostate tumors; all these tests have been widely used in the clinic.