LAUSR

Introduction: This study aimed to determine the efficacy and safety of robotic-based fractionated stereotactic radiotherapy (FSRT) in the treatment of large brainstem metastases (BSMs). Methods: Ten BSM were treated in ten patients with FSRT between January 2012 and December 2018. The median age was 61 years (range, 53–74 years) with a median Karnofsky Performance Score of 80 (range, 70–90). Four patients (40%) had received whole-brain radiotherapy prior to FSRT. The median tumor volume was 4.2 cm3 (range, 1.35–8.18 cm3) with a median prescription dose of 24 Gy (range, 16–24 Gy) delivered in 3–5 fractions (median three fractions) to the 56%–83% isodose line (median 70.5%). Results: 1Median follow-up for the entire cohort was 14.1 months (range, 4.6–19.3 months). Five local recurrences were documented. Local control (LC) rate at 6 and 12 months was 90% and 64.2%, respectively. The median tumor volume of patients developing local recurrence was 5.42 cm3. Three patients experienced intracranial out-of-field failure for a 12-month intracranial control rate of 78.7%. Median overall survival and time to extracranial progression were 14.7 and 16.8 months, respectively. Toxicity was low with only one patient developing a new hemiparesis. Conclusion: Robotic-based FSRT for BSM appears to be safe with favorable LC and low toxicity even for large tumors.