Resected pancreatic neuroendocrine tumors: Patterns of failure and disease-related outcomes with or without radiotherapy.

Abstract

325 Background: Pancreatic neuroendocrine tumors (NET) are rare with improved prognosis compared to adenocarcinomas. Surgical resection remains the standard of care although many patients present with unresectable/metastatic disease. While many resected patients will fail distantly, little is known regarding the use of adjuvant radiotherapy. To define this and establish specific patterns of failure, an analysis of resected patients from a single institution was performed. Methods: From 1994 to 2009, 33 patients with NET of the pancreatic head underwent resection with curative intent at Duke University. Sixteen patients were treated with surgical resection alone, and an additional 17 underwent resection with adjuvant (n=10) or neoadjuvant (n=7) radiation therapy, usually with concurrent fluoropyrimidine-based chemotherapy (CMT). Median radiation dose was 50.4 Gy and median follow-up 28 months. Results: Patients receiving radiation therapy were more likely to have involved nodes (47% vs 19%, p=0.09), more mitoses per high power field (p=0.10) and involved margins (47% vs 31%, p=0.20) compared to surgery alone patients. Median survival for the whole cohort was 52 months. Two-year survival was 68% for the CMT group and 93% for the surgery alone group (p=0.03). Two-year local control was 85% for the CMT and 90% for the surgery group (p=0.49). Two-year metastasis-free survival was 45% and 69% for the CMT and surgery patients, respectively (p=0.02). Conclusions: Patients receiving CMT were more likely to have adverse pathologic features compared to surgery-alone patients. Survival outcomes were high in both groups, although less so in the CMT group. Distant metastasis development dominated patterns of failure. Local failure following resection of NETs is uncommon, and the role of adjuvant radiotherapy in this setting remains unclear. No significant financial relationships to disclose.