RE-IRRADIATION PRACTICES AND OUTCOMES IN PATIENTS WITH DIPG/DMG: A REPORT FROM THE INTERNATIONAL DIPG REGISTRY

Abstract

BACKGROUND: Given that radiation therapy is the only treatment modality demonstrated to result in any clinical benefit for children with DIPG, re-irradiation therapy has been explored as a treatment option for progressive DIPG. Several studies suggest re-irradiation is feasible, and may lengthen survival for children with progressive DIPG. However, any re-irradiation benefits are unclear and no standard of care (dose, fractionation, volume, timing, clinical status) has been defined. The aims of this study are to evaluate re-radiation therapy practices for children with progressive DIPG/DMG and to define a historical cohort of children with DIPG/ DMG who have received re-radiation (re-XRT) for progressive DIPG/DMG. METHODS: Data was extracted from the International DIPG Registry, and analyzed with descriptive statistics. RESULTS: Of 1214 patients in the iDIPG Registry, 113 receiving re-XRT. Patients were diagnosed between 2002-2022, with the majority of patients diagnosed over the last decade. Of those 113 patients with specified data, at re-irradiation, n=68 (60%) received photon and n= 4 (4%) were treated with proton radiation. The median dose at re-XRT was 25 Gy (20-30 IQR) in 10 fractions (10-14 IQR). Time between initial XRT and re-XRT was 41.5 weeks (29.5-54 weeks). OS from diagnosis was 18 months (range, 15-23 mo); OS from re-XRT was 6 months (range, 4-10 mo). CONCLUSIONS: Re-radiation therapy for children with DIPG/DMG is becoming a more common practice and appears to have OS benefit, with post-progression OS of 6 mo comparing favorably to historical data of 2.3 mo. [Cooney T et al, Neuro Oncol 2017] Efforts are underway to define patient selection and tolerability. Data extraction from the SIOPE DIPG/DMG Registry is also ongoing; data from both registries will be collated and uniformly presented.