Simultaneous Integrated Boost Technique for Pediatric High-Grade Gliomas: A Single-Institution Experience

Abstract

<h3>Purpose/Objective(s)</h3> The prognosis for pediatric patients with high grade glioma (HGG) remains dismal despite aggressive multidisciplinary treatment, and there is marked variability regarding the optimal radiation approach. We report outcomes from a retrospective review of pediatric patients with HGG treated using a simultaneous integrated boost (SIB) technique at a single institution. <h3>Materials/Methods</h3> The medical records of patients ages 0–22y with biopsy-proven non-DIPG localized HGG treated with radiotherapy (RT) from January 2006 to May 2021 were retrospectively reviewed on an IRB approved protocol. Endpoints were Kaplan-Meier estimates of overall survival (OS) and progression free survival (PFS), and patterns of failure. <h3>Results</h3> There were 32 patients in the cohort; 24 patients had glioblastoma without further molecular characterization, 2 had H3 K27M mutant diffuse midline gliomas, 2 had G34R mutant glioma, 2 had glioblastoma with IDH1 mutation, 1 had high-grade astrocytoma, and 1 had high-grade glial neoplasm. Median age at diagnosis was 14.9 (1.9–21.5) years. Prior to RT, 6 patients obtained both spinal MRIs and lumbar punctures, 5 obtained spinal MRIs, and 1 had a lumbar puncture; none had evidence of distant metastases. All patients were treated with intensity modulated radiotherapy (IMRT) using SIB with two dose levels. The most common (n=25) dose to the high dose volume was 60 Gy (range, 40–60 Gy); the most common (n=24) dose to the low dose volume was 50 Gy (range, 30–55 Gy). Treatment was most commonly (n=26) delivered in 30 fractions (range, 15-33). One patient did not complete planned RT due to tumor hemorrhage. Median follow up for all patients was 17 (0–164.4) months. For patients who completed planned RT, median PFS was 20.1 (1–140) months from RT start. Median OS was 25.9 months with one- and two-year survival rates of 80% and 56%, respectively. Of 19 patients with known recurrence, 8 recurred locally, 7 recurred in the distant brain, and 4 developed leptomeningeal dissemination. Three patients were alive at 10 years after initial diagnosis; none of these patients were known to have tumors with IDH mutations. <h3>Conclusion</h3> This study explores outcomes in a cohort of pediatric HGG patients treated with SIB technique, with encouraging initial results. Future efforts will be necessary to identify additional molecular and treatment factors that impact outcome.