LAUSR

e15693 Background: Resection of the primary tumor in metastatic neuroendocrine tumor (NET) is controversial. The aim of this study is to evaluate survival outcomes and identify prognostic variables of surgical resection of the primary tumor in metastatic NET patients. Methods: Data were obtained from all US hospitals that contributed to the National Cancer Database (NCDB) between 2004 and 2013. Chi-square and ANOVA tests were done to identify factors associated with surgical modality. Univariate and multivariate cox proportional hazards models were used for association between patient characteristics and survival. Kaplan-Meier curves were generated and log-rank tests conducted to compare the survival difference of patient characteristics. Results: A total of 2,361 patients between 18 and 90 years of age with stage IV well/intermediate-differentiated NET were identified. The mean age was 62.1 years (SD±13), with an equal male to female ratio (50.0%). Majority of NET primaries were in the small intestine (33.0%), pancreas (26.3%), and lung (24.4%). The majority were well differentiated tumors (69.6%) and 42.5% of patients underwent surgery at the primary site. On multivariate analysis total surgical resection of the primary (HR 0.44; 0.22-0.90; p < 0.001), female sex, year of diagnosis 2010-2014, negative surgical margin, Charlson-Deyo score < 2, and age < 51 years at diagnosis were associated with better overall survival (OS). Conclusions: Resection of the primary in stage IV well/intermediate-differentiated NET was associated with improved 5-year OS compared to patients with no surgery in small intestine (60.1% vs 44.2%), lung (70.0% vs 20.2%), and pancreas tumors (59.3% vs 30.6%).