LAUSR

446 Background: Surgical management of metastatic midgut neuroendocrine tumors (NET) remains controversial. Resection of primary tumor only without liver resection is advocated only in select patients, frequently for palliation. Additionally, no standard algorithm exists, and the risk profile for these patients is not well documented in the literature. We evaluated these midgut NETs with liver metastasis in the National Cancer Data Base (NCDB) to determine if resection of the primary tumor only affected survival outcomes. Methods: The NCDB was queried to identify patients with liver only metastatic midgut NET tumors between 2010 and 2015. Patients who underwent surgery of their liver metastasis were excluded. The cohort was separated into two groups, those who underwent resection of the primary tumor and those who did not. Patient demographics, year of diagnosis, clinicopathologic tumor characteristics and Charlson/Deyo comorbidity index were compared among the two groups. The primary outcome was overall survival (OS). Kaplan-Meier estimates were used to predict OS. Results: One-thousand nine hundred fifty-two patients with median age of 63 were identified. Median tumor size was 2.4 cm. Of these, 1,295 (66.0%) patients underwent resection of the primary tumor and 667 (34.0%) did not. Patients undergoing resection were younger (median age 63 vs. 65, p < 0.001) and had smaller tumors (median 2.3 cm vs. 3.0 cm, p < 0.001). There was no difference between the groups with respect to sex, year of diagnosis or Charlson/Deyo Comorbidity Score. Median follow up time was 42.8 months (IQR 29.7). A total of 483 deaths occurred in the entire cohort with a 5-year OS of 60.8%. The 5-year OS for patients undergoing resection of the primary tumor was 65.9% and 49.3% for those not undergoing resection (p < 0.001). Conclusions: Patients with liver only metastatic midgut neuroendocrine tumors had an overall survival advantage when the primary tumor was resected. Patients with liver only metastatic midgut NET may benefit from surgical resection and should be evaluated for surgery at the time of diagnosis.