Blood screening for cancer refers to the method of checking for cancer through the blood, and the accuracy of blood screening for cancer is generally closely related to the type of cancer suffered and the different stages of the disease process of the cancer suffered. For example, patients with acute leukemia, also known as acute blood cancer, have a very high accuracy rate of blood screening. More than 90% of patients can find abnormalities through routine blood tests, suggesting leukemia, and the diagnosis can often be confirmed through bone marrow aspiration. However, patients with malignant tumors in other parts of the body, often in the early stages of the disease, the accuracy of blood screening is not high, less than 50%, because the tumor markers are usually found in other parts of the tumor. But in the early stage of the tumor, the concentration of some of the tumor markers is elevated. When the disease progresses or recurs, the tumor markers can only increase significantly, and then the accuracy of blood screening will increase significantly, and can reach more than 90%.