There is no most accurate indicator for cancer, but there are three indicators that are more widely used in testing organizations as well as in hospitals, mainly including: alpha-fetoprotein (AFP), carcinoembryonic antigen, and glycoconjugate antigen CA19-9, and according to these three lab tests, they can assist in clinical diagnosis. 1. Alpha-fetoprotein (AFP): it is a specific marker for diagnosing hepatocellular carcinoma, widely used in liver cancer screening, diagnosis, judgment of treatment effect and prediction of recurrence. AFP greater than 400ng/ml is one of the conditions for diagnosing liver cancer. If AFP gradually rises but does not fall or if AFP is greater than 200ng/ml for 8 weeks, it should be analyzed together with imaging and changes in liver function or observed dynamically. 2. Carcinoembryonic antigen: mainly for gastric cancer, lung cancer, etc. Carcinoembryonic antigen may be elevated in both cancers. 3. CA19-9: CA19-9 is a sensitive tumor marker for digestive system, and obvious elevation is common in digestive tract tumors, usually seen in pancreatic cancer, colorectal cancer and rectal cancer. However, the above indicators alone cannot confirm the diagnosis of cancer, and it needs to be further combined with imaging and pathological examination to make a clear diagnosis, identify the cause of the disease and actively treat it.