160 The Role of CyberKnife Stereotactic Radiosurgery in Recurrent Cranial Medulloblastomas Across Pediatric and Adult Populations

INTRODUCTION: Medulloblastoma is the most common malignant brain tumor in children. Recent advancements have reshaped the therapeutic landscape, with stereotactic radiosurgery (SRS) emerging as a promising treatment option for recurrent cases. METHODS: We conducted a retrospective analysis of clinical and radiological records of patients who underwent CyberKnife SRS for recurrent cranial medulloblastomas at our institution between 1998 and 2023. Follow-up data were available for 15 medulloblastomas in 10 patients, comprising 8 pediatric patients (ages 3-18) and 2 adults (ages 19-75). The median age at SRS treatment was 13 years, with a median tumor volume of 1.9 cc. The median single-fraction equivalent dose was 18 Gy. RESULTS: Following a median follow-up of 39 months (range: 6-78), 53.3% of the medulloblastomas progressed, 13.3% regressed, and 33.3% remained stable. The 3-year local tumor control rate was 65%, with lower rates in adults (50%) and higher rates in pediatric patients (67%). The 3-year overall survival rate was 70%, significantly higher in pediatric patients (75%) compared to adults (50%). The 3-year progression-free survival rate was 58.3%, with pediatric patients showing higher rates (60%) compared to adults (50%). Two pediatric patients developed radiation-induced edema, while two adult patients experienced radiation necrosis, resulting in their demise at the latest follow-up. CONCLUSIONS: Our study presents a thorough assessment of CyberKnife SRS efficacy and safety in managing recurrent cranial medulloblastomas across diverse age groups. The infrequent occurrence of adverse radiation events reaffirms the safety of SRS, enhancing its therapeutic value. Symptomatic outcomes, shaped by factors like age, tumor site, and surgical history, underscore the need for individualized treatment modalities. Our findings underscore the importance of ongoing research and the advancement of tailored therapeutic strategies for recurrent medulloblastomas.