Resection with intraoperative radiotherapy vs. adjuvant radiotherapy in the treatment of eloquent brain metastases: an analysis of feasibility and safety

Abstract

Introduction: The treatment of motor eloquent brain metastases (BM) harbors an elevated risk of neurological deficits due to possible damage to motor-cortex and tracts. Preserving a good functional and neurological status is crucial to enable comprehensive oncologic treatment. Growing evidence promotes intraoperative radiotherapy (IORT) with low voltage x-rays as alternative to adjuvant external beam radiotherapy (EBRT). Aim of this study is to investigate the safety and feasibility of surgery with IORT in motor eloquent regions compared to adjuvant radiotherapy (RT). Methods: We performed a retrospective chart review analysis of patients undergoing surgery for motor eloquent BMs at our institution with either IORT or adjuvant RT. All patients were resected under intraoperative neuromonitoring (IONM). We compared patient characteristics, the rate of neurological deficits along with IONM parameters, functional status (KPS) and adverse events (AE) in both groups. Results: 33 patients were analyzed from which 25 underwent IORT and 8 adjuvant EBRT in motor eloquent BMs. New motor deficits occurred in 7/33 patients without significant difference between both groups after 30 days (IORT 4/25 vs. adj. RT 3/8; Chi [2]-test: p = 0.19). The KPS after surgery did not differ significantly between both groups (IORT: 90% [72.5–90] vs. adj. RT: 80% [70–90]; Mann-Whitney-U-test: p = 0.31). No patient experienced local tumor recurrence or radio necrosis. 9/33 patients experienced postoperative AEs until the 30 day follow up without significantly different rates between both groups (IORT 5/25 vs. adj. RT 4/8; Chi [2]-test: p = 0.09). Conclusion: 50 kV photon IORT is a safe treatment option for motor eloquent BMs and does not seem to provoke in symptomatic brain irritation.