Glycoantigen CA19-9 is a mucin-type glycoprotein substance that is mainly found in the pancreas and bile duct epithelium of adults, and it is also a gastrointestinal tumor-associated antigen. Although the glycoantigen CA19-9 is also significantly elevated in cholangiocarcinoma, hepatocellular carcinoma, gastric carcinoma, and colorectal carcinoma, CA19-9 is more significantly elevated in pancreatic cancer, and its sensitivity and specificity are higher, which can reach over 90%. In addition, it has been found that the level of CA19-9 is also closely related to the stage of the tumor, which can also be used for postoperative follow-up observation of pancreatic cancer to determine whether there is recurrence and metastasis. Of course, not only malignant tumors of the digestive system can cause elevated CA19-9, but also malignant tumors such as ovarian cancer, lymphoma and breast cancer, which can also show mild elevation, however, the positive rate is low. In contrast, benign diseases such as chronic pancreatitis, cholelithiasis, cirrhosis, renal insufficiency, and diabetes can also show mild elevation of CA19-9, although it is usually transient.