Hypofractionated stereotactic body radiation therapy (SBRT) in pediatric patients: results of a national prospective multicenter study

Abstract

<h3>Objectives</h3> Efficiency and toxicity of hypofractionated Stereotactic Body Radiation Therapy (SBRT) in pediatric situations need to be assessed. We conducted a prospective multicentric National study on SBRT in young patients (1.5-20 y.) <h3>Methods</h3> Indications of SBRT had to be approved by a multi-disciplinary tumor board. SBRT indications were either locally relapsed ependymoma after complete surgery (randomization between 24 Gy/3 fr or 25 Gy/5 fr, isodose 80%), or brain, lung or spinal metastases of any origin after incomplete or no resection in first-line, or in re-irradiation (re-RT) situations The main objective was to evaluate the 6-month local control (LC) rate (RECIST 1.1). Secondary objectives were to evaluate 1 and 2-year LC rates, acute (< 3 months) and medium-term toxicities (3-24 months) using NCI-CTC-v-4.0. <h3>Results</h3> Sixty-one patients, median age 13y., (range 3-20) were included in 10 institutions (12/2013-12/2019). Four patients did finally not receive SBRT and were excluded from the analysis. Eighteen patients (32%) were irradiated in first intention (5 brain, 5 lung, 8 spinal lesions, median dose 35 Gy/5fr, isodose 80%. Thirty-nine patients (68 %) were included for re-RT: 14 patients (7 patients/randomization arm) for post-operative SBRT for locally relapsed ependymoma, 25 patients for re-RT in other situations (brain, spine, lung…) (median dose 25 Gy/5 fr, isodose 80%). No pt required general anesthesia. Median follow-up was 24 months (22-28 months). Six-month, 1- and 2-year local control rates will be reported during the congress (undergoing analysis). Gr.2 and 3 acute RT toxicities were observed in 7 and 1 (epilepsy) patients respectively. Medium-term RT toxicity was identified in 4 patients (gr.2) and 1 patients (gr.3, brain radio-necrosis). No grade 4/5 was reported. <h3>Conclusion</h3> SBRT is feasible and safe in childhood in selected brain, lung and spine treatment or in selected cases of re-RT. More details (especially efficiency) will be available for the congress.