Local treatment of neuroendocrine liver metastases - How effective and safe is stereotactic microwave ablation?

Abstract Background The less invasiveness of local ablation techniques such as stereotactic microwave ablation (SMWA) for the treatment of malignant hepatic lesions has made it an attractive alternative to conventional surgical resection. Aims The aim of this retrospective study was to assess the successful ablation rate of neuroendocrine tumor liver metastases (NETLM) 3 months after SMWA, the recurrence-free survival time, as well as the rate of peri- and early post interventional complications. Methods Retrospective analysis including all patients treated with SMWA for NETLM in our institution between 03/2015 and 07/2022. SMWA was performed as per the decision of the interdisciplinary tumorboard. Patients were included independent of location of primary tumors, disease stage, prior treatments. Patients underwent follow-up imaging (FU) every 1-6 months. Results 41 metastases were ablated in 21 interventions in 17 patients with a mean age of 63.6±9.7 years. A median of two lesions (range 1-4) were ablated per intervention. Mean time until first FU was 2.8±1.5 months. 39 of 41 (95.1%) lesions were fully ablated at the first FU. The two incompletely ablated lesions were treated using re-ablation and systemic treatment, respectively. A local recurrence occurred in further two ablation zones (4.9%) after 3.6 years in a patient with a progressive disease. Remaining 37 (90.2%) patients had no tumor recurrence in the ablation zone at the latest available FU (mean 24.3±17.3 months). Postinterventional length of hospital stay was a median of 1 [IQR 1;1.5]. No complications higher than Clavien Dindo Grade II occurred. Conclusions SMWA is a good minimal invasive intervention for the treatment of NETLM with low morbidity and high local efficacy.