Resection of primary tumor site is associated with prolonged survival in metastatic nonfunctioning pancreatic neuroendocrine tumors

Background. Nonfunctioning pancreatic neuroendocrine tumors (NFpNET) present with distant metastases in up to 50% of patients. It is unknown whether removal of the primary tumor in patients with NFpNET and metastases is beneficial. Methods. We used the Surveillance, Epidemiology, and End Results database to identify patients with NFpNET and distant metastases. The primary outcome measure in this study was overall survival. Results. We identified 882 patients with metastatic NFpNET who had survival data; 303 (34%) patients had operative removal of their primary tumor of which 243 (80%) were grade I or II. Median survival of patients undergoing resection of the primary site was 65 (95% confidence interval 60-86) versus 10 (8-12) months for those without resection (P < .0001). Patients diagnosed after 2003 (n = 625, 71%) were more likely to undergo an operation than those diagnosed earlier (P = .001). Multivariable analysis showed that a lesser tumor grade (P < .0001), younger age (P < .0001), diagnosis during or after 2003 (P = .0003), tumor site in the body/tail (P = .009), and operative resection of the primary tumor site (P < .0001) were associated with prolonged survival of patients with NFpNET and distant metastases. Conclusion. This study suggests that resection of the site of the primary NFpNET is associated with greater survival in patients with distant metastases and could therefore be considered as a additional treatment option in this patient population.