Five-Fraction Stereotactic Radiotherapy for Brain Metastases: A Single-Institution Experience on Different Dose Schedules.

INTRODUCTION: The most common intracranial neoplasm diagnosed in adults are brain metastases (BrM). The benefit in terms of clinical control and toxicity for stereotactic radiotherapy (SRT) has been investigated for patients with low load of BrM. AIM: The aim of this single-institution experience was to investigate the best dose schedule for five-fraction SRT (FFSRT). METHODS: A retrospective analysis of patients treated for BrM with different dose schedules of FFSRT was performed. Local control (LC) and clinical outcomes were evaluated with magnetic resonance imaging at 3, 6, and 9 months. Toxicity data were also collected. RESULTS: A total of 41 patients treated from November 2016 to September 2020 were enrolled in the analysis. Non-small cell lung cancer (51.2%) and breast cancer (24.3%) represented the most frequent primitive tumors. Treatment was performed on 5 consecutive days with prescribed dose ranging from 30 to 40 Gy, prescribed to the 95% isodose line that covered at least 98% of the gross tumor volume. Statistically significant differences (p = 0.025) with higher LC rates for dose schedules >6 Gy for fractions. Toxicity rates were not found to be higher than G1. CONCLUSION: The results of this retrospective analysis suggest that FFSRT for BrM seems to be safe and feasible. Our results also underline that a total dose lower than 30 Gy in 5 fractions should not be used due to the expected minor LC.