Objective: The aim of this study was to determine outcomes of primary tumor resection in metastatic neuroendocrine tumors across all primary tumor sites.
Background: Primary tumor resection (PTR) may offer a survival benefit in metastatic gastrointestinal neuroendocrine tumors (GI-NETs); however, few studies have examined the effect of primary site and grade on resection and survival.
Methods: This is a retrospective study of patients with metastatic GI-NETs at presentation between 2005 and 2011 using the California Cancer Registry (CCR) dataset merged with California Office of Statewide Health Planning and Development (OSHPD) inpatient longitudinal database. Primary outcome was overall survival (OS). Univariate and multivariate (MV) analyses were performed using the Pearson Chi-squared tests and Cox proportional hazard, respectively. OS was estimated using the Kaplan-Meier method and log-rank test.
Results: A total of 854 patients with GI-NET metastases on presentation underwent 392 PTRs. Liver metastases occurred in 430 patients; 240 received liver treatment(s). PTR improved OS in patients with untreated metastases (median survival 10 vs 38 months, P < 0.001). On MV analysis adjusted for demographics, tumor stage, grade, chemotherapy use, Charlson comorbidity index, primary tumor location, or treatment of liver metastases, PTR with/without liver treatment improved OS in comparison to no treatment [hazard ratio (HR) 0.50, P < 0.001 and 0.39, P < 0.001, respectively]. PTR offered a survival benefit across all grades (low-grade, HR 0.38, P = 0.002 and high-grade, HR 0.62, P = 0.025) CONCLUSION:: PTR in GI-NET is associated with a better survival, with or without liver treatment, irrespective of grade. This study supports the resection of the primary tumor in patients with metastatic GI-NETs, independent of liver treatment.