ESTRO 2025 - Abstract Book

S1621

Clinical – äediatric tumours

ESTRO 2025

Conclusion: We report a shorter overall survival in patients treated with HF compared to CF in our institution. In a resource limited setting, hypofractionation offers a practical alternative option to reduce treatment burden. However, this data and evolving evidence supporting the use of re-irradiation in DIPG may influence clinicians to favour CF over HF as the initial treatment strategy.

Keywords: Fractionation, Pontine Glioma

References: 1) Zaghloul MS, Eldebawy E, Ahmed S, Mousa AG, Amin A, Refaat A, Zaky I, Elkhateeb N, Sabry M. Hypofractionated conformal radiotherapy for pediatric diffuse intrinsic pontine glioma (DIPG): a randomized controlled trial. Radiother Oncol. 2014 Apr;111(1):35-40. doi: 10.1016/j.radonc.2014.01.013. 2)Lu VM, Welby JP, Mahajan A, Laack NN, Daniels DJ. Reirradiation for diffuse intrinsic pontine glioma: a systematic review and meta-analysis. Childs Nerv Syst. 2019 May;35(5):739-746. doi: 10.1007/s00381-019-04118-y.

1276

Poster Discussion Palliative Re-irradiation Improves Survival in Progressive Diffuse Infiltrative Pontine Glioma Alper Kahvecioglu 1 , Mustafa Cengiz 1 , Guzide Burca Aydin 2 , Mustafa Tezer Kutluk 2 , Gokcen Coban Cifci 3 , Gozde Yazici 1 1 Radiation Oncology, Hacettepe University Faculty of Medicine, Ankara, Turkey. 2 Pediatric Oncology, Hacettepe University Faculty of Medicine, Ankara, Turkey. 3 Radiology, Hacettepe University Faculty of Medicine, Ankara, Turkey Purpose/Objective: This study aims to assess the oncological outcomes in children and young adults with diffuse infiltrative pontine glioma (DIPG) who have progressed after initial radiotherapy (RT), with an emphasis on the role of re-irradiation. Material/Methods: We retrospectively analyzed the records of 33 patients aged 25 or younger who were diagnosed with DIPG and treated with initial RT between 2000 and 2023. All patients progressed after initial RT, and 15 of them received re irradiation in combination with systemic therapy. The remaining 18 patients were treated with salvage systemic therapy alone. Statistical analysis, including descriptive statistics, overall survival (OS), and progression-free survival (PFS), was performed using the Statistical Package for the Social Sciences version 23.0 (IBM, Armonk, NY, USA). Results: The median age at diagnosis was 8 years (range, 4–24 years), with a median initial RT dose of 54 Gy (range, 39–54 Gy). The median interval between initial RT and progression was 8 months (range, 3–40 months). For re-irradiation, the median dose was 23.4 Gy (range, 19.8–36 Gy). Among patients who underwent re-irradiation, the time from initial RT to progression was 11 months (range, 3–40 months), compared to 9 months (range, 4–35 months) in those who did not receive re-irradiation (p=0.25). The median OS and PFS from diagnosis were 18 months (range, 8–84 months) and 8 months (range, 3–40 months), respectively, while the median OS after progression was 6 months (range, 1–44 months). For patients receiving re-irradiation, the 1-year post-progression OS was 27%, versus 0% in those treated with systemic therapy alone ( p=0.01 , Figure 1). Multivariate analysis results, shown in Table 1, identified re-irradiation as the sole independent positive prognostic factor for post-progression OS (HR: 1.9, 95% CI: 0.2–1.1, p=0.008 ). Among the 15 re-irradiated patients, 9 of 12 with available data (75%) reported improvements in neurological symptoms after re-irradiation. No patient experienced acute or late RT-related ≥ grade 3 toxicity. Figure 1. Kaplan-Meier curve showing overall survival following progression.