Impact of concomitant systemic treatments on toxicity and intracerebral response after stereotactic radiotherapy for brain metastases 

Abstract

Background: The aim of this study was to determine the safety and efficacy of fractionated stereotactic radiotherapy (SRT) in combination with systemic therapies (ST) for brain metastases (BM). Methods: 99 patients (171 BM) received SRT and concurrent ST (group 1) and 95 patients (131 BM) received SRT alone without concurrent ST (group 2). SRT was planned on a linear accelerator, using volumetric modulated arc therapy. All ST were allowed including chemotherapy (CT), immunotherapy (IT), targeted therapy (TT) and hormonotherapy (HT). Treatment was considered to be concurrent if the timing between the drug administration and SRT did not exceed 1 month. IT was used concurrently with SRT in 30 patients. Local control (LC), freedom for distant brain metastases (FFDBM), overall survival (OS) and radionecrosis (RN) were evaluated. Variables analyzed included histology, age, gender, diagnosis-specific Graded Prognostic Assessment score, recursive partitioning analysis score, number of BM, presence of extracranial metastases, tumor volume, Karnofsky performance status and the timing of ST. Results: After a median follow-up of 11.9 months (range 0.7-29.7), there was no significant difference between the two groups. However, patients who received concurrent IT had better 1-year LC, FFDBM and RN rate compared to patient who did not: 96% versus 78% (p=0.02), 76% versus 53% (p=0.004) and 80% versus 90% (p=0.03), respectively. In multivariate analysis, concurrent IT (p=0.022) and tumor volume <2.07cc (p=0.039) were significantly correlated with improvement of LC. The addition of IT to SRT compared to SRT alone was associated with an increased risk of RN (p=0.03).Conclusion: SRT delivered concurrently with IT improved LC, FFDBM, OS with a higher RN rate.