Radiofrequency and microwave ablation controls hepatic oligoprogression of advanced gastroenteropancreatic neuroendocrine tumors

In progression of multifocal liver metastases of gastroenteropancreatic neuroendocrine tumors (GEP-NET) escalation of systemic therapy is indicated. The aim of this retrospective study was to investigate the potential of local thermal ablation in hepatic oligoprogression and otherwise stable disease in GEP-NET. Patients with hepatic oligoprogression and otherwise stable disease, who underwent radiofrequency ablation (RFA) or microwave ablation (MWA) for local control, were included in the study. Thermal ablation was performed while maintaining the ongoing systemic therapy or without addition of a systemic therapy. The effectiveness of this therapeutic approach was evaluated by determination of local treatment success, improvement of progression-free survival (PFS) and the safety. Seventeen thermal ablation procedures were performed in 13 patients with well differentiated NET including seven ileum NET, four pancreatic NET, one appendix NET and one rectum NET. RFA and MWA of liver metastases were well tolerated without major complications. Thermal ablation resulted in an estimated median PFS of 62.6 weeks (mean 50.5 weeks; range 10.1-78.9 weeks) per procedure. In four patients, two ablation procedures were performed throughout the course of their disease resulting in an estimated median PFS of 69.1 weeks (mean 71.6 weeks; range 10.1-123.1 weeks) per patient. Start or change of systemic therapy could be delayed up to 123.1 weeks by using thermal ablations for isolated progression of single liver metastases. 88% of thermal ablations prolonged PFS. Thermal ablation of liver metastases in a non-curative intent has the potential to provide focal growth control and to prolong PFS in GEP-NET patients with hepatic oligoprogression.