Stereotactic Radiosurgery for Recurrent Primary and Metastatic CNS Malignancies in the Pediatric Population

Background The safety and efficacy of stereotactic radiosurgery (SRS) in pediatric malignant central nervous system (CNS) tumors are not well established. This study evaluates disease control and toxicity outcomes following SRS in this population. Methods 53 SRS treatments in 35 pediatric patients (age ≤21) with primary (n = 27) or metastatic (n = 8) CNS malignancies treated between 2000–2023 were retrospectively reviewed. Kaplan-Meier and Cox proportional hazards analyses were performed. Results Median age at SRS was 12 years (IQR 6.6–16.3); 71% had prior external beam radiation to the brain. Median follow-up was 33 months. SRS was delivered in a single fraction in 91% (median dose 18 Gy). Median gross tumor volume was 1.3cc (IQR 0.36–4.1) for single-fraction and 23.2cc (IQR 10.5–23.2) for fractionated SRS. The 1-year local control rate was 81.4%. 3-year intracranial progression-free survival (IC-PFS) and overall survival were 19.9% and 59.3%, respectively. Distant brain recurrence without local failure occurred in 54% at a median of 8 months. Patients treated for a single lesion had superior 3-year IC-PFS compared with those with 2–4 or ≥ 5 lesions (29.2% vs. 6.7% and 0%, p = 0.01). Two patients (5%) developed grade ≥3 adverse radiation effects (AREs), both related to treatment effect within one year after SRS. No associations were found between ARE and dosimetric parameters or prior radiation. Conclusion SRS provides effective local control with low toxicity in pediatric malignant CNS tumors. Although there remains a substantial risk of distant CNS failures after SRS, all patients were able to receive additional salvage therapy including re-irradiation.