Impact of radionuclide therapy on survival outcomes for de novo metastatic gastroenteropancreatic neuroendocrine tumors: A population-based cohort study.

4144 Background: De novo metastatic gastroenteropancreatic neuroendocrine tumors (dmGEP-NETs) are difficult to treat without the option of radical surgery. The aim of this study was to investigate the survival outcomes of radionuclide therapy. Methods: Patients diagnosed with dmGEP-NETs from the Surveillance, Epidemiology, and End Results (SEER)-17 registry database (2000–2021) were included in this study. The impact of radionuclide therapy on overall survival (OS) and cancer-specific survival (CSS) was assessed using univariate Kaplan-Meier method and multivariate Cox regression analysis. Results: From 2010 to 2021, a total of 9657 patients at diagnosis years with dmGEP-NETs were determined from the SEER database. On the univariate analysis, patients with dmGEP-NETs who received radionuclide therapy significantly obtained better OS (5-year rate: 55.6% vs. 37.9%; p <0.001) and CSS (5-year rate: 58.2% vs. 44.2%; p <0.001) than patients without radionuclide therapy. Finally, the significant clinical factors associated with OS and CSS were included into multivariate Cox regression analysis to investigate the independent prognostic value of radionuclide therapy. The results showed that radionuclide therapy was an independent prognostic factor for OS (hazard ratio [HR], 0.530; 95% confidence interval [CI], 0.348-0.808; p=0.003) and CSS (HR, 0.508; 95%CI, 0.319-0.808; p=0.004) in patients diagnosed with dmGEP-NETs. Besides, radionuclide therapy was associated with better OS (p <0.001) and CSS (p <0.001) compared to beam radiation. Conclusions: Radionuclide therapy was associated with improved survival in patients with de novo metastatic gastroenteropancreatic neuroendocrine tumors.