2388 - Survival and Neurologic Outcomes after Re-Irradiation in Children with Diffuse Midline Glioma and Diffuse Intrinsic Pontine Glioma
Presenter(s)
T. L. Vaziri1, D. Vyas1, M. Al-Humaid1, C. H. Lucas2, M. Guryildirim3, L. Kilburn4, R. D. Gartrell5, M. Koldobskiy5, E. Raabe5, K. Cohen5, M. Ladra1, and S. Acharya1; 1Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 2Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, 3Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, 4Division of Oncology, Children's National Medical Center, Washington, DC, 5Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD
Purpose/Objective(s): Re-irradiation (reRT) is increasingly offered following progression for patients with diffuse intrinsic pontine glioma (DIPG) and diffuse midline glioma (DMG), but patient selection remains challenging as prognostic factors are not well understood. This study evaluated clinical outcomes after reRT in a contemporary cohort of patients with DIPG/DMG.
Materials/Methods: Patients <26 years old with DMG/DIPG treated with radiotherapy between 2011 and 2025 were retrospectively reviewed. Primary endpoints included overall survival (OS2) and progression-free survival (PFS2), measured from first progression, and change in neurologic symptoms after reRT. Survival was estimated using the Kaplan–Meier method, and Cox proportional hazards models were used to identify prognostic factors.
Results: Fifty-eight patients were included, of whom 37 (63.8%) underwent reRT. Tumors were predominantly pontine (74.1%). Median time to first progression was 8.70 months. Patients treated with reRT vs. no reRT demonstrated higher rates of improvement in motor function (51.4% vs. 9.5%, p=0.002), cranial nerve function (29.7% vs. 4.8%, p=0.044), and gait ataxia (35.1% vs. 9.5%, p=0.059). Median OS2 and PFS2 were improved with reRT vs. no reRT (OS2: 9.67 vs. 2.57 months, p<0.001; PFS2: 5.63 vs. 1.57 months, p<0.001). OS2 was independently associated with reRT (HR 0.27, 95% CI: 0.14–0.51, p <0.0001), pontine location (HR: 2.94, 95% CI: 1.40–6.15, p=.004), and use of steroids at first progression (HR: 4.12, 95% CI:1.83–9.29, p =.001). PFS2 was independently associated with reRT (HR: 0.23, 95% CI: 0.12–0.42, p <0.0001) and distant pattern of failure (distant brain vs. local failure: HR 2.83, 95% CI 1.07–7.51, p=.037; distant spine and brain vs. local failure: HR 2.49, 95% CI 1.17–5.30, p=.018). Among reRT-treated patients, non-pontine vs. pontine location was associated with improved OS2 (6.23 vs. 12.97 months, 95% CI: 5.03–10 vs. 4.87–18.9 months, p=0.020), and local vs. distant failure was associated with improved PFS2 (median PFS2: 2.20 vs. 6.30 months, 95% CI: 0.67–5.77 vs. 4.97–9.13 months, p=0.0029).
Conclusion: Re-irradiation was associated with neurologic improvement and a moderate seven-month extension of overall survival from first progression in patients with DIPG/DMG. Patients with non-pontine tumors or local-only failure might derive the greatest benefit. Prospective studies are warranted to define optimal dose/fractionation and characterize prognostic factors to guide patient selection for both pontine and non-pontine tumor locations.