It is possible that the blood test for tumor may not be detected. Most tumors cannot be detected by ordinary blood tests, such as routine blood tests and liver and kidney functions. Of course, if we check tumor markers, that is, some cancer cell indices, we may be able to detect them. For example, if we check tumor marker AFP, which is greater than 400ug/L for one month, combined with the imaging examination of occupied liver, we can make the clinical diagnosis of primary liver cancer, of course, we also need to see whether there are lesions in other parts. In the case of pancreatic cancer, a clinical diagnosis of pancreatic cancer can also be made if the index of glycoantigen 19-9 is elevated more than 400 kU/L, and then combined with imaging examinations to find an occupancy in the pancreas. However, the results of blood test alone cannot confirm the diagnosis of cancer. The diagnosis of cancer must be combined with imaging and the gold standard for the final diagnosis is pathological examination.