Stereotactic Ablative Radiotherapy for the Management of Liver Metastases from Neuroendocrine Neoplasms: A Preliminary Study

Abstract

Introduction: Liver metastases are common in patients with neuroendocrine neoplasms. The role of stereotactic ablative radiotherapy (SABR) is not well understood in this population. Objective: To evaluate the safety and efficacy of SABR in treating well-differentiated neuroendocrine liver metastases (WD-NELM). Methods: A retrospective review of patients with WD-NELM treated with SABR between January 2015-July 2019. Demographic, treatment and clinical/radiographic follow-up data were abstracted. RECIST 1.1 criteria were applied to each individual target to evaluate the response to treatment. Local control (LC) and progression free survival (PFS) were determined using Kaplan-Meier methodology. Toxicity was reported according to CTCAE v5.0. Results: Twenty-five patients with a total of 53 liver metastases treated with SABR were identified. Most patients (68%) had midgut tumors, were Grade II (80%) and had high volume intrahepatic and/or extrahepatic disease (76%). Median number of liver metastases treated was 2 with a median size of 2.5 cm. Median radiation dose delivered was 50Gy/5 fractions. Median follow-up was 14 months; 24 of the 25 patients were alive at time of analysis. The objective response rate (ORR) was 32%, with improvement or stability in 96% of lesions treated. The median time to best response was 9 months. The 1-year LC and PFS were 92% and 44% respectively. No Grade III/IV acute or late toxicity was identified. Conclusions: Liver SABR is a safe and promising means of providing local control for WD-NELM. This treatment modality should be evaluated in select patients in concert with strategies to manage systemic disease.