There is not an absolute relationship between tumor markers and pancreatic cancer, such as certain pancreatic cancer patients can not express tumor marker antigen, thus showing normal tumor marker levels. Ca199 is a kind of glycan antigen, which belongs to tumor marker. Significant elevation of this index is often seen in malignant tumors of pancreas, gastric cancer, colon cancer, rectal cancer, lung cancer, etc. It has high specificity for the diagnosis of pancreatic cancer, but it is not absolute. When ca199 is found to be significantly elevated, it needs to be combined with the results of imaging and pathology to evaluate whether there is a malignant tumor of the pancreas or malignant tumor of the digestive tract, but the final diagnosis is still based on pathological examination. A part of patients with pancreatic cancer have normal ca199 index, which means that their epithelium does not obviously express ca199, not all patients with pancreatic cancer have elevated ca199, but the sensitivity and specificity of this index for the diagnosis of pancreatic malignant tumors are stronger. Some studies say that the sensitivity of diagnosing pancreatic cancer is 79%~81% and the specificity is 82%~90%. In conclusion, tumor markers are not the gold standard for diagnosis and have no absolute relationship with a certain sensitivity. Therefore, patients with pancreatic cancer may have normal levels of tumor markers; a combination of imaging and pathological examinations is needed to make a judgment. If pancreatic cancer is suspected or diagnosed, it is recommended to go to regular hospitals for comprehensive assessment of the condition and follow the doctor’s instructions to cooperate with the treatment, so as not to delay the condition.