Hypo-fractionated stereotactic radiotherapy alone using volumetric modulated arc therapy for patients with single, large brain metastases unsuitable for surgical resection

Background: Hypo-fractionated stereotactic radiotherapy (HSRT) is emerging as a valid treatment option for patients with single, large brain metastases (BMs). We analyzed a set of our patients treated with HSRT. The aim of this study was to evaluate local control (LC), brain distant progression (BDP), toxicity and overall survival (OS). Methods: From July 2011 to May 2015, 102 patients underwent HSRT consisting of 27Gy/3fractions for lesions 2.1-3 cm and 32Gy/4 fractions for lesions 3.1-5 cm. Local progression was defined as increase of the enhancing abnormality on MRI, and distant progression as new brain metastases outside the irradiated volume. Toxicity in terms of radio-necrosis was assessed using contrast enhanced T1MRI, T2 weighted-MRI and perfusion- MRI. Result: The median maximum diameter of BM was 2.9 cm (range 2.1-5 cm), the median gross target volume (GTV) was 16.3 cm3 and the median planning target volume (PTV) was 33.7 cm3 The median,1,2-year local control rate was 30 months, 96, 96 %; the median, 1-2-year rate of BDP was 24 months, 12, 24 %; the median,1,2-year OS was 14 months, 69, 33 %. KPS and controlled extracranial disease were associated with significant survival benefit (p <0.01). Brain radio-necrosis occurred in six patients (5.8 %). Conclusion: In patients with single, large BMs unsuitable for surgical resection, HSRT is a safe and feasible treatment, with good brain local control and limited toxicity.