Pancreatic polypeptide secreting tumors – an ins- titutional experience and review of the literature

Objectives: We present a retrospective analysis of patients with pancreatic neuroendocrine tumors (PNETs) who have had Pancreatic Polypeptide testing in an attempt to better define Pancreatic Polypeptide producing tumors as an entity and the role of Pancreatic Polypeptide (PP) as a biomarker. To our knowledge, this is the first single center comprehensive review of Pancreatic Polypeptide producing tumors. Methods: A retrospective study of patients with pancreatic neuroendocrine tumors seen at our institution from 1980 to 2011. All patients that have had PP concentrations measured at least once were evaluated. Data relating to diagnosis, pathology, surgery, liver directed therapies, chemotherapy and survival outcome were noted. Results: 71 patients with PNETs fulfilled the inclusion criteria (8 PPomas, 22 PP producing tumors and 41 non -PP producing tumors). We identified a trend towards better survival for patients with PP producing tumors vs. non- PP producing tumors (p=0.19). There was no correlation between survival and a diagnosis of PPoma in relation to other PP producing tumors or non-PP producing tumors. There was a borderline significant positive correlation of PP in association with Chromogranin A in a postoperative setting (p=0.061). Conclusions: Pancreatic Polypeptide is a biomarker that is worth prospective investigation and a standardized assay. Our analysis investigating Pancreatic Polypeptide as a prognostic and or predictive biomarker reveals a trend towards showing these characteristics. Using a standardized test and investigating this biomarker prospectively could lead to the validation of Pancreatic Polypeptide as a biomarker.