Survival after surgery for metastatic small bowel compared to pancreatic neuroendocrine tumors.

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221 Background: Surgical management of small bowel (mSBNET) and pancreatic (mPNET) neuroendocrine tumors with hepatic metastases remains controversial. Previous studies, often drawn from single institution experiences, combine outcomes mSBNET and mPNET cohorts, despite ample evidence indicating discreet biology and natural history. This study aimed to define and contrast survival outcomes after surgery in patients with mSBNET and mPNET using a large national dataset. Methods: Patients with hepatic metastases from SBNET and PNET who underwent surgical (n = 1063; n = 556, respectively) or non-surgical management (n = 456; n = 2593, respectively) were identified in the National Cancer Database (1998-2014). Surgical and non-surgical cohorts were matched (1:1) by propensity scores based on the likelihood of receiving surgery and survival hazard. Kaplan-Meier estimates of overall survival (OS) were compared. Results: After adjustment for potential cofounders (age, Charleston comorbidity index, tumor differentiation and administration of chemotherapy or radiotherapy), nonsurgical management was associated with poorer survival in SBNET (HR 2 95%CI 1.5-2.7) and in PNET (HR 3.6, 98%CI 2.8-4.5). In the propensity matched cohort, there was a significant survival advantage for patients who received surgery for both SBNET and PNET (p < 0.001). In SBNET, mean survival in the non-surgical cohort was 33.9 months (SD 1.3, 95%CI 31.5-36.4), and 39.3 months in the surgical cohort (SD 0.8, 95%CI 36.1-39.1). In PNET, mean survival in the non-surgical cohort was 32.7 months (SD 1.6, 95%CI 29.5-35.8), and 55.1 months in the surgical cohort (SD 1.4, 95%CI 52.4-57.7). Conclusions: Surgical selection or management are associated with a survival advantage in both mPNET and mSBNET; this advantage is greater in mPNET. The relative contributions of patient selection and therapeutic benefit require further elucidation.