2669 - Long-Term Safety and Efficacy of SRS for Nonmalignant CNS Indications in Children and Young Adults
Presenter(s)
E. J. Smith1, C. C. Baniel1, Y. P. Wang1, S. D. Chang2, I. C. Gibbs1, J. Oh3, E. L. Pollom1, E. Rahimy1, S. G. Soltys1, and S. M. Hiniker1; 1Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, 2Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, 3Department of Radiation Oncology, BC Cancer, Vancouver, BC, Canada
Purpose/Objective(s): Stereotactic radiosurgery (SRS) is a standard treatment approach in adults with central nervous system (CNS) conditions, including both malignant and benign processes. However, the use of SRS in pediatric conditions has not been well documented, particularly in the cases of benign conditions, and there is concern for malignant transformation or development of secondary malignancy with radiation in younger patients. We hypothesized that SRS for nonmalignant pediatric CNS disease was safe and effective with long-term follow-up.
Materials/Methods: At a single institution, we retrospectively analyzed consecutive pediatric and young adult patients under 25 years old who underwent SRS to the brain or cervical spine for nonmalignant conditions between 1999 and 2024. We excluded patients who had prior external beam radiation and those who underwent SRS for vascular abnormalities. Treatments were performed with a robotic frameless SRS system. Targets were contoured as gross tumor volume without additional planning margin. Descriptive statistics are presented for patient demographics, treatment characteristics, toxicities (CTCAE v5), local control, and secondary malignancy.
Results: 38 patients with 43 treated targets were included. The median age at first SRS was 18 years old (range 2-24 years). Nine (23.7%) patients had neurofibromatosis 2 (NF2) and 3 patients (7.9%) had Von Hippel-Lindau (VHL) disease. The most common conditions were schwannoma (44.2%), hemangioblastoma (11.6%), craniopharyngioma (9.3%), meningioma (7%), and pituitary adenoma (7%). Median treatment volume was 1.33 cc (range 0.04-30.3 cc). The median dose was 21 Gy over a median of 2 fractions, prescribed to a median 80% isodose line. With 403.3 person-years of follow-up (median 11.6 years), no patients experienced malignant transformation or secondary malignancies, including 84.1 person-years in those with NF2. Local control at 5 years was 97.7% and at 10 years was 93.0%. 26.3% (n=10) had new disease develop outside of the radiation field, all of whom had either NF2 or VHL. No patients experienced grade 4+ acute or late toxicities. Three patients (7.9%) experienced acute side effects, including nausea, dizziness, and ear pain (all grade 1). Seven patients (18.4%) developed late side effects, 2 of which resolved with intervention. Of the 63.2% (n=24) patients who experienced disease-related symptoms prior to SRS, 29.2% (n=7) had resolution of their symptoms after SRS, 66.7% (n=16) had no change in their symptoms, and 4.2% (n=1) had worsening of their symptoms.
Conclusion: With 403.3 person-years of follow-up, no pediatric or young adult patients treated with SRS for benign conditions experienced malignant transformation or secondary malignancy. Local control, symptom improvement, and toxicity rates are comparable to historical reports. This supports the safety and efficacy of SRS in younger patients for benign CNS conditions, though larger, prospective studies are needed to validate these findings.