Safety and initial efficacy of radiation segmentectomy for the treatment of hepatic metastases

Background: Hepatic metastatectomy and ablation are associated with prolonged survival, but not all lesions are anatomically amenable to these therapies. We evaluated safety and initial efficacy of segmental ablative transarterial radioembolization, or radiation segmentectomy (RS), as a treatment for hepatic metastases. Methods: A single institution retrospective analysis was performed of patients with hepatic metastases, determined unamenable to resection by a multidisciplinary tumor board, treated with RS from 2015-2017. Safety parameters evaluated were pre and post procedure liver chemistry, MELD score, ALBI grade, platelet count, and adverse events using both Common Terminology Criteria for Adverse Events (CTCAE) v 4.0 and Clavien Dindo (CD) classifications. Initial efficacy was evaluated using RECIST, mRECIST, and PERCIST criteria. Results: Ten patients underwent between 1-3 RS treatments. There was no clinical treatment toxicity or significant post-treatment change in liver chemistry, MELD, or ALBI score. One patient had a CTCAE Grade 1/CD Grade 1 adverse event. All patients showed partial or complete imaging response at initial assessment (1-3 months). Seven patients demonstrated disease control at a mean of 7.1 months post treatment. Three patients developed out of field disease progression. One RS was technically unsuccessful. Conclusions: Early evaluation of segmental radioembolization suggests a safe treatment option for select patients with hepatic metastases. Initial efficacy as definitive radiotherapy with minimal toxicity is promising in anatomic locations unamenable to resection or alternative means of ablation.