RONC-17. STEREOTACTIC RADIOSURGERY FOR SPINE METASTASES IN PEDIATRIC MALIGNANCIES

BACKGROUND: Spine stereotactic radiosurgery (SSRS) is a non-invasive technique that delivers ablative radiotherapy for optimal control of bony disease. While SSRS is known to provide excellent local control (LC) and minimal toxicity in adults, the role of SSRS in pediatrics is less clear. PURPOSE: To evaluate SSRS in pediatric patients with spinal metastases. METHODS: A retrospective review of patients (<18 yrs) treated with SSRS at MDACC was performed after IRB approval. Descriptive statistics were utilized for analysis. RESULTS: From 2011–2019, 12 metastatic osseous sites (3 cervical, 4 thoracic, 5 lumbar-sacral) in 9 patients were treated. Median follow-up was 9 months (range 2–41). Six males (67%) and 3 females (33%) all KPS ≥70, received radiation to ≤3 contiguous vertebral bodies. Median age was 16 yrs (range 8–18). No patients required sedation. Histologies included 7 osteosarcomas, one rhabdomyosarcoma and one Ewing’s sarcoma. Metastatic epidural spinal cord compression scores ranged from 0 (6), 1b (3) and 3 (3). No sites had surgery prior to SSRS and one site received prior conventional radiation. SSRS doses included 24 Gy in 1 fraction (7), 24–27 Gy in 3 fractions (4) and 50 Gy in 5 fractions (1). Six-month LC was 83% with one local failure following 27 Gy. OS at 6 and 12 mo were 55% and 23%. There was no grade ≥3 acute toxicity, no radiation myelopathy or vertebral compression fractures. CONCLUSION: In this initial report, SSRS represents a promising modality that is well tolerated and provides excellent LC. However, further follow-up is warranted in the pediatric setting.