Outcomes of therasphere radioembolization for neuroendocrine metastases.

Abstract

371 Background: Neuroendocrine tumors (NET) are a rare group of tumors with variable biologic activity that have a propensity for hepatic metastases. Complete surgical resection or debulking is the standard of care while chemotherapy is reserved for unresectable disease. However, liver directed therapy utilizing radioembolization with yttrium-90 (y90) may offer an alternative modality of treatment to patients with unresectable hepatic disease while minimizing systemic toxicity and providing acceptable overall survival (OS). Methods: A retrospective review of all patients undergoing y90 microsphere treatment for metastatic NET (mNET) from 2009-2013 was conducted. Patient, treatment, and post-treatment variables from initial diagnosis and y90 treatment were collected. Multivariable analysis (MVA) of factors related to OS and treatment toxicity was performed by the Cox proportional hazard model using Wald test and OS estimates were calculated using the Kaplan-Meier method. Results: We identified 74 patients with a median follow-up of 21 months. Median and 2 year OS was 26 months and 56%. Tumor burden was a significant predictor of survival. Two year OS for patients with ≤ 25%, 25-50%, 50-75%, and >75% tumor burden was 63%, 59%, 40%, and 34%, respectively (log-rank p = 0.027). MVA revealed that female gender and higher disease burden were associated with increased mortality; age, location of primary tumor, resection status of the primary tumor, prior chemotherapy, and presence of extrahepatic metastases at the time of treatment were not significant predictors of OS. The majority of patients (88%) experienced a treatment related toxicity; however 72% were Grade 1/2 and only 16% were Grade 3/4. Male gender and prior liver therapy were associated with higher rates of toxicity. Conclusions: Y90 was associated with acceptable OS with minimal severe morbidity in this series of patients with mNET. Lower tumor burden and male gender were associated with better OS. These results suggest that y90 may be a potential treatment alternative for patients with unresectable mNET. Prospective studies evaluating y90 in the treatment of unresectable chemo-refractory mNET are needed.