Malignant tumors can be detected through blood tests, and in the clinical examination of malignant tumors through hematology, it is mainly to check various tumor indicators, commonly used, such as alpha-fetoprotein, carcinoembryonic antigen, CA199, CA125. Elevation of the above tumor indicators suggests that malignant tumors may be combined with malignant tumors, for example, alpha-fetoprotein indicates that liver cancer is combined with malignant tumors, carcinoembryonic antigen is seen in the tumors of the gastrointestinal tract, elevation of CA199 can be Elevated CA199 can be seen in gastrointestinal malignant tumors or pancreatic cancer, and CA125 can be seen in gastrointestinal malignant tumors or gynecological tumors. At present, in the early stage of malignant tumors, the elevation of hematological tumor indexes may not necessarily occur, but after the diagnosis of malignant tumors, the hematological tumor indexes will be examined in order to guide or predict the prognosis of the patients.