Clinical outcomes and efficacy of stereotactic body radiation therapy in children, adolescents, and young adults with metastatic solid tumors

Objective: The objective of this study is to report disease outcomes and toxicity with the use of stereotactic body radiation therapy (SBRT) in the treatment of pediatric metastatic disease. Methods: All pediatric and adolescent young adult (AYA) patients’ who received SBRT were included between the years 2000 and 2020. Study endpoints included local control (LC), progression-free survival (PFS), overall survival (OS), cumulative incidence (CI) of death or local failure and toxicity. The end points with respect to survival and LC were calculated using the Kaplan–Meier estimate. The cumulative incidence of local failure was calculated using death as a competing risk. Results: 16 patients with 36 lesions irradiated met inclusion criteria and formed the study cohort. The median OS and PFS for the entire cohort were 17 months and 15.7 months, respectively. The 1 year OS for the entire cohort was 75%. The 6-and 12 month local control was 85 and 78%, respectively. There were no local failures in irradiated lesions for patients who received a BED₁₀≥100 Gy. Patients who were treated with SBRT who had ≤5 meta-static lesions at first recurrence had a superior 1 year OS of 100 vs 50% for those with >5 lesions. One patient (6.3%) experienced a Grade 3 central nervous system toxicity. Conclusion: LC was excellent with SBRT delivered to metastatic disease, particularly for lesions receiving a BED₁₀≥100 Gy. High-grade toxicity was rare in our patient population. Patients with five or fewer metastatic sites have a significantly Vbetter OS compared to >5 sites. Advances in knowledge: This study demonstrates that SBRT is safe and efficacious in the treatment of pediatric oligometastatic disease.