Cancer is a generic term for a large group of malignant tumors that generally have a low chance of being misdiagnosed. The diagnosis of cancer must be confirmed by pathological examination, that is, by puncture cytology or biopsy and post-surgical pathology to determine the nature. Other examinations including imaging, enhanced CT, MRI, etc. are only able to make preliminary diagnosis, and combined with tumor markers, some cases can be clinically diagnosed, but there is no way to confirm the diagnosis, and the diagnosis must rely on pathological examination. However, some malignant tumors in clinical practice are more difficult to obtain pathology, like pancreatic malignant tumors, because of the deep location, there is a possibility to do puncture of the pancreas, but it is relatively risky and may not be punctured. In this case, when combined with tumor markers, the elevation of glycoantigen 199 or CA19-9 is greater than 400 U/ml, and then the imaging examination reveals an occupancy in the pancreas, the clinical diagnosis of pancreatic cancer can be made, but the clinical diagnosis cannot replace the pathological diagnosis.