Intestinal-type and pancreatobiliary-type adenocarcinomas: how does ampullary carcinoma differ from other periampullary malignancies?

Background: Ampullary carcinomas typically have either intestinal or pancreatobiliary type of differentiation, histopathologically resembling carcinomas of its adjacent tissues (duodenum, bile duct, or pancreas). We evaluated whether the histologic type itself is more important for long-term survival than the fact that the tumor originated in the ampulla.
Methods: Microscopic slides from 207 consecutive pancreatoduodenectomies were reviewed (72 pancreatic, 46 biliary, 61 ampullary, and 28 duodenal adenocarcinomas; 76 intestinal type, 131 pancreatobiliary type). Tumor size, nodal involvement, margin involvement, degree of differentiation, vascular involvement, and perineural growth, as well as overall survival, were compared between different origins of the same histologic type.
Results: Intestinal-type ampullary adenocarcinomas had similar frequency of poor histopathologic factors compared to duodenal adenocarcinomas, and pancreatobiliary-type ampullary adenocarcinomas had similar frequency of poor histopathologic factors compared to pancreatobiliary-type biliary and pancreatic adenocarcinomas. Adjusting for tumor size and nodal involvement, there was no difference in long-term survival between patients with intestinal-type ampullary, duodenal, or biliary and pancreatic tumors (p = 0.79), and there was no difference in long-term survival between patients with pancreatobiliary-type ampullary, biliary, or pancreatic tumors (p = 0.41).
Conclusions: Long-term survival for patients with ampullary carcinomas equals pancreatic, biliary, and duodenal carcinomas when the same histologic type is compared. It can be questioned whether ampullary carcinomas should be regarded as a separate entity in classification of solid tumors. Clinical trials on adjuvant treatments for periampullary carcinomas should stratify by pancreatobiliary type versus intestinal type of histologic differentiation.