Effectiveness of radioembolization of metastatic neuroendocrine tumors of the liver refractory to chemotherapy

To evaluate the effectiveness and outcomes of Yttrium-90 radioembolization treatment of metastatic neuroendocrine tumor of the liver, which is refractory to prior treatment. Forty-three consecutive patients (mean age, 61; 26 male, 17 female) with metastatic neuroendocrine tumor (NET) to the liver who had progressed on systemic chemotherapy were treated with either resin (n = 30) or glass (n = 13) Yttrium-90 microspheres at a single center between 2009-2014, using a sequential lobar approach. Thirteen patients had radiographic evidence of extra-hepatic disease at the time of treatment, independent of the presence or absence of their primary lesion. Twenty patients had not undergone resection of their primary tumor. Response to treatment was measured on follow up imaging using both mRECIST and EASL criteria for necrosis. Progression-free and overall survivals were evaluated using Kaplan-Meier estimates. Assessment was also made of symptom-relief in those patients presenting with tumor-related symptoms. Toxicities were evaluated using Common Terminology Criteria for Adverse Events (CTCAEv4.0). The average activity delivered was 1.12 GBq for the resin and 3.32 for the glass microspheres. The median follow up was 16 months (range, 1-74 months). The median overall survival (OS) was 41 months. The 1 and 2 year OS was 84% (95% CI 74-97%) and 73% (95% CI 58-90%). Median time to hepatic progression was 18 months, with 1 year hepatic progression free survival (PFS) of 78% (95% CI 65-93%) and 2 year hepatic PFS of 48% (95% CI 33 – 71%). The median overall PFS was 16 months. Overall PFS at 1 year was 62% (95% CI 48-80%) and at 2 years was 37% (95% CI 23 – 59%). Five patients (12%) had documented grade 3-4 toxicities. Of the 17 with carcinoid symptoms, 5 (29%) had documented improvement after treatment. Treating refractory neuroendocrine liver metastases using Yttrium-90 radioembolization is safe, effective, and leads to satisfactory tumor response and patient survival.