Resection of Primary Gastrointestinal Neuroendocrine Tumor Among Patients with Non-Resected Metastases Is Associated with Improved Survival: A SEER-Medicare Analysis.

BACKGROUND The objective of this study was to analyze whether primary tumor resection (PTR) among patients with stage IV gastrointestinal neuroendocrine tumor (GI-NET) and unresected metastases was associated with improved outcomes. METHODS Patients diagnosed with stage IV GI-NETs were identified in the linked SEER-Medicare database from 2004 to 2015. Overall survival (OS) of patients who did versus did not undergo PTR was examined using bivariate and multivariable cox regression analysis as well as propensity score matching (PSM). RESULTS Among 2219 patients with metastatic GI-NETs, 632 (28.5%) underwent PTR, whereas 1587 (71.5%) did not. The majority of individuals had a NET in the pancreas (n = 969, 43.6%); the most common site of metastatic disease was the liver (n = 1064, 47.9%). Patients with stage IV small intestinal NETs most frequently underwent PTR (62.6%) followed by individuals with colon NETs (56.5%). After adjusting for all competing factors, PTR remained independently associated with improved OS (HR = 0.65, 95% CI: 0.56-0.76). Following PSM (n = 236 per group), patients who underwent PTR had improved OS (median OS: 1.3 years vs 0.8 years, p = 0.016). While PTR of NETs originating from stomach, small intestine, colon, and pancreas was associated with improved OS, PTR of rectal NET did not yield a survival benefit. CONCLUSION Primary GI-NET resection was associated with a survival benefit among individuals presenting with metastatic GI-NET with unresected metastases. Resection of primary GI-NET among patients with stage IV disease and unresected metastases should only be performed in selected cases following multi-disciplinary evaluation.