Primary Tumor Resection Offers Survival Benefit in Patients with Metastatic Midgut Neuroendocrine Tumors

Background Approximately 35% of patients with midgut neuroendocrine tumors (MNET) present with distant metastases. Although successful resection of these metastatic foci improves overall survival (OS), the role of primary tumor resection (PTR) in patients with unresectable metastatic disease is unclear. The aim of this study is to evaluate prevalence and survival impact of PTR in patients with unresectable metastatic MNET. Patients and Methods A retrospective cohort study of patients with metastatic MNET was performed using the National Cancer Database (2004-2014). Demographic and clinicopathologic variables were compared between patients who did and did not undergo PTR. Survival analysis was performed using Kaplan-Meier and log-rank tests. Multivariable regression analysis was used to assess factors associated with PTR and all-cause mortality. Results The cohort included 4076 patients; 2520 (61.8%) underwent PTR. Patients more likely to undergo PTR were younger and diagnosed earlier, underwent treatment at a nonacademic facility, lived on the West Coast or in the Central USA, and presented with smaller lower-grade small bowel primary tumors. Median OS was improved for patients who underwent PTR compared with those who did not (71 vs. 29 months, p < 0.001). On multivariable analysis, younger age, Black race, higher income, later year of diagnosis, treatment at an academic facility, private insurance, fewer comorbidities, small bowel primary, lower grade, and PTR (hazard ratio 0.63, 95% confidence interval 0.51-0.78, p < 0.001) were associated with lower mortality. Conclusions PTR was associated with improved OS. Further study is needed to understand how clinicians select patients for PTR.