There are many tumor markers, the common ones such as normal value of alpha-fetoprotein is less than 25ug/L, carcinoembryonic antigen is less than 5ug/L and so on. 1. Alpha-fetoprotein: at present, it is mainly used for diagnosis of primary liver cancer and monitoring of therapeutic efficacy, and its normal value is less than 25ug/L. Some other malignant tumors, benign diseases, pregnancy and so on can also lead to the elevation of alpha-fetoprotein, which needs to be combined with other tests to make a comprehensive judgment. 2. Carcinoembryonic antigen: the normal value is less than 5ug/L. It is mainly used in colorectal cancer, gastric cancer, pancreatic cancer, lung cancer, breast cancer and other diseases, with low value in early diagnosis, and is mainly used in observing the efficacy of tumor treatment and judging the prognosis. 3. Prostate-specific antigen: the normal value is less than 4ug/L, which is the first choice for diagnosing prostate cancer. Besides, prostatitis, prostate hypertrophy, nephritis and so on can also show its elevation, so the influence of benign prostate diseases cannot be excluded. In addition to the above, there are other tumor markers such as Glyco Antigen 125, Glyco Antigen 19-9, etc. If abnormal elevation of tumor markers occurs, it is recommended to consult a doctor in time to make a clear diagnosis and receive standardized treatment.