Glycoantigen 19-9, also known as CA19-9, is a relatively specific tumor marker for the pancreas. Generally speaking, if the CA19-9 index is greater than 400, and then combined with the imaging examination, it is found that there is an occupying lesion in the pancreas, which indicates that pancreatic cancer is more likely. Generally, it is difficult to do pathological examination of the pancreas, but the clinical diagnosis can be made through the tumor marker CA19-9 index and imaging examination. However, if it is slightly elevated, pancreatitis or some other tumors, such as gastrointestinal tumors, may also cause mild elevation, which cannot be fully confirmed at this time, and needs to be combined with other tests such as gastroscopy, colonoscopy and abdominal CT to determine. Generally, after the diagnosis of pancreatic cancer is confirmed, it also depends on whether there are metastatic lesions elsewhere. Pancreatic tumors are more malignant, and if surgery can be done, it is usually very early stage. Most of them are found to be middle to late stage and there is no way to operate, so after treatment or after surgery and radiotherapy, this index can also be checked, which can be used as a follow-up indicator to observe the effect of treatment.