Poor prognosis of common-type invasive ductal carcinomas that originate in the branching pancreatic duct.

Purpose: To clarify the incidence, clinicopathological features and prognosis of pancreatic invasive ductal carcinomas (IDCs) with different tumor origin sites in the pancreatic duct.

Methods: Based on the relationship between the invasive cancer area (ICA) and the main pancreatic duct (MPD), IDCs less than 2 cm in diameter were classified into two groups: type I, in which the ICA and MPD were separated, and type II, in which the MPD passed through the ICA. The clinicopathological findings and prognosis of each type were compared in a total of 37 patients.