First experience and clinical results using a new non-coplanar mono-isocenter technique (HyperArc) for Linac-based VMAT radiosurgery in brain metastases

IntroductionRadiosurgery (SRS) or stereotactic fractionated radiotherapy (SFRT) is increasing in the treatment of brain metastases (BMs). Aim of the present study was to evaluate the safety and effectiveness of SRS/SFRT for BMs, using a new mono-isocenter non-coplanar solution (HyperArc Varian Medical System).MethodsBMs patients with a diameter inferior to 3cm, a life expectancy of more than 3months and a good performance status, were eligible for Linac-based volumetric modulated arc therapy (VMAT) SFRT/SRS with HyperArc. A retrospective analysis of patients and BMs was performed.ResultsFrom August 2017 to May 2018, 381BMs in 64 patients were treated and 246BMs (43 patients, median number of BMs: 5) of them were suitable for analysis. With a median FU time of 6 months, 244 out 246 (99%) BMs were controlled (18% complete response; 41% partial response, 40% stable disease), 2BMs showed a progression, at the first control. No acute or late toxicities were reported. Median overall survival (OS) has not yet been achieved, while median time to progression was 5months. In univariate analysis, statistically negative prognostic factors for OS were histology of primary tumor (p=0.009): lung/breast cancer had better survival rates as compared to others. Cumulative intracranial volume disease15cc and systemic progression disease were independent prognostic factors for OS at univariate (p=0.04; p=0.005) and multivariate (p=0.04; p=0.009) analysis, respectively.ConclusionThe present first clinical data show that SFRT/SRS with HyperArc is safe and effective for BMs patients. The utilization of SFRT/SRS for BMs is promising and should be further explored in randomized trials.