Tumor markers, also known as tumor markers, are substances characteristically present in malignant tumor cells, or produced abnormally by malignant tumor cells, or produced by the host in response to tumor stimulation, and are a class of substances that can reflect tumor occurrence and development and monitor tumor response to therapy. Tumor markers exist in tissues, body fluids and excretions of tumor patients, and can be detected by immunological, biological and chemical methods. Normal reference value of alpha-fetoprotein (AFP): ≤20 ng/ml AFP is by far the most sensitive and specific indicator for early diagnosis of primary liver cancer, and is suitable for screening of large susceptible populations because of its cheapness and ease of detection. Significantly elevated AFP generally indicates primary hepatocellular carcinoma, but a negative test does not exclude it. Usually, two months after surgical resection of hepatocellular carcinoma, AFP value should continue to decrease, otherwise there is a possibility of recurrence and metastasis. AFP may also be elevated in germline embryonal carcinoma, ovarian endodermal sinus carcinoma, alcoholic cirrhosis, acute hepatitis, certain gastrointestinal cancers, and HBsAg carriers. Normal reference value of carcinoembryonic antigen (CEA): ≤5 ng/ml CEA is an important tumor-associated antigen. 70-90% of patients with colon adenocarcinoma are positive for CEA, followed by gastric cancer, pancreatic cancer, liver cancer, etc. When liver metastasis occurs, the elevation of CEA is especially obvious. The sensitivity of CEA detection for postoperative recurrence of tumor can reach more than 80%, often earlier than clinical, pathological examination and X-ray examination. An elevation in both tests two weeks after surgery is indicative of tumor recurrence and metastasis. Normal reference value of cancer antigen 19-9 (CA19-9): ≤27 U/ml The positive rate of CA19-9 in gastric cancer, colorectal cancer, gallbladder cancer, bile duct cancer and liver cancer will be high. CA19-9 concentration can also be increased in pancreatitis, mild biliary depression and jaundice. Cancer antigen 125 (CA125) normal reference value: ≤35 U/ml CA125 is the preferred marker for ovarian cancer and endometrial cancer, and is currently the most important index used for early diagnosis, efficacy observation, prognosis judgment, and monitoring of recurrence and metastasis of ovarian cancer. Prostate specific antigen (PSA) normal reference value: ≤4.400 ng/ml PSA is a specific marker for prostate cancer. Elevated serum TPSA generally indicates the presence of prostate lesions (prostatitis, benign hyperplasia or cancer) and is an organ-specific tumor marker, which is one of the most important indicators for the detection and early detection of prostate cancer. Free prostate-specific antigen (FPSA) FPSA/TPSA: > 0.15 Patients with prostate cancer have a significantly lower FPSA/TPSA ratio. Patients with benign prostatic hyperplasia had a significantly higher FPSA/TPSA ratio. EBV antibodies (EBV-VCA) EBV positivity may be a high risk factor for nasopharyngeal carcinoma, and positive individuals have a much greater chance of developing nasopharyngeal carcinoma than negative individuals.