A high CA19-9 should be considered inflammation of the GI tract or GI tumors, such as gastric cancer, pancreatic cancer, bile duct cancer and colorectal cancer. It also needs to be combined with CT or MRI plain plus enhancement of upper abdomen and whole abdomen, as well as gastroscopy and colonoscopy, and finally pathological examination as the gold standard for tumor diagnosis. CA19-9 is significantly elevated in patients with bowel cancer, gastric cancer and liver cancer. CA19-9 is also elevated to varying degrees in acute pancreatitis, cholecystitis, cholestatic cholangitis, cirrhosis, hepatitis and other diseases.