90Y radioembolization in the treatment of neuroendocrine neoplasms: Results of an international multicenter retrospective study.

In neuroendocrine neoplasms (NEN), the presence of distant metastases has a severe impact on survival leading to a relevant decrease of the 5-year survival rate. Here, 90Y radioembolization (RE) might be an important treatment option, however, data to support clinical benefits for RE are scarce. Therefore, the purpose of this study was to analyze the use of RE in NEN patients with hepatic metastases in an international, multi-center retrospective analysis and assess the potential role of RE in a multimodal treatment concept. Methods: 297 angiographic evaluations in NEN patients prior to RE were analyzed. Baseline characteristics and parameters derived from imaging evaluation and RE were analyzed. Tumor response was assessed using RECIST 1.1 and survival data were collected. Mean overall survival (OS) between different groups was compared using Kaplan Meier curves and the log rank test. p<0.05 indicated statistical significance. Results: After RE, disease control rate according to RECIST 1.1 was 83.5% after three and 50.9% after twelve months. OS in the entire population was 38.9±33.0 months. High tumor grade (p<0.006) and high tumor burden (P = 0.001) were both associated with a significant decrease of OS. The presence of extrahepatic metastases (P = 0.335) and the type of metastatic vascularization pattern (P = 0.460) had no influence on OS. Patients who received RE as second-line therapy had a slightly longer but not statistically significant OS than patients who had RE in a salvage setting (44.8 vs. 30.6 months, P = 0.078). Hepatic and global progression-free survival after RE was significantly decreased in heavily pretreated patients than patients with second-line therapy (P = 0.011 and P = 0.010, respectively). Conclusion: RE could be an important alternative to peptide receptor radionuclide therapy as second-line treatment in patients with progressive liver-dominant disease pretreated with somatostatin analogs.