ESTRO 2025 - Abstract Book

S1638

Clinical – äediatric tumours

ESTRO 2025

75.1), and 49.4% (95% CI 43.3-55.3). There was a majority of Posterior Fossa-A EPN subtype (PFA-EPN) after molecular classification (144 patients). Among the 319 patients, in multivariate analysis, factors significantly associated with lower RFS, was grade 3 (p<0.001) and with worse OS were lateralized tumors (p=0.029), incomplete surgery evaluated by surgeon (p=0.002), time between first surgery and RT ≥ 6 months (p=0.023) and grade 3 (p=0.011). Gain 1 q was significant in univariate analysis of RFS (p=0.039) and OS (p<0.01). Cumulative incidence of relapse analysis showed that RT dose ≤ 54 Gy (p=0.02), grade 3 (p=0.001) and XRT (p=0.04), were associated with higher risk of local relapse. However, median Follow-up after XRT and PBT were respectively 119.0 months 77.2 months (p<0.01), which may explain difference in cumulative incidence of local relapse Conclusion: Higher grade, lateralized tumors, incomplete surgery, large delay between surgery and RT were associated with worse OS. Lower dose was associated with a higher incidence of local relapses. The work is ongoing to complete the molecular classification and integrate it in future multivariate analysis.

Keywords: Ependymoma, children, brain tumor

References: [1]

[1] A. Ducassou et al. , “Pediatric Localized Intracranial Ependymomas: A Multicenter Analysis of the Société Française de lutte contre les Cancers de l’Enfant (SFCE) from 2000 to 2013,” Int J Radiat Oncol Biol Phys , vol. 102, no. 1, pp. 166–173, 2018, doi: 10.1016/j.ijrobp.2018.05.036. [2] [2] F. Tensaouti et al. , “Patterns of failure after radiotherapy for pediatric patients with intracranial ependymoma,” Radiotherapy and Oncology , vol. 122, no. 3, pp. 362–367, 2017, doi: 10.1016/j.radonc.2016.12.025.

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Digital Poster Postoperative radiotherapy in WHO grade 2 intracranial ependymoma: A SEER Analysis Patricia J Ong Radiation Oncology, University of Santo Tomas Hospital, Quezon City, Philippines

Purpose/Objective: There is limited and conflicting evidence regarding the benefit of postoperative radiation therapy for grade 2 resected intracranial ependymoma. We analyzed data from the Surveillance, Epidemiology, and End Results (SEER) database to investigate the benefit of postoperative radiation therapy in this patient population. Material/Methods: We queried the SEER database for WHO Grade 2 intracranial ependymoma cases diagnosed from 2000 to 2020 who underwent surgical resection of the mass. We excluded ependymoma tumors outside of the central nervous system and those recorded as uncertain locations, no adjuvant treatment given, and survival of less than 1 month. We compared those who received postoperative RT compared to those who do not, with overall survival as the primary endpoint. Descriptive, univariate and multivariate statistical analysis, and Cox proportional hazards regression were done. Kaplan Meier curves were done to estimate survival. Results: A total of 268 patients were included in the analysis. Postoperative radiotherapy did not improve overall survival in Grade 2 ependymoma (RR 1.19, 95%CI: 0.93-1.52). Hazard ratio changed after adjustment with size and primary site. Final adjusted model to age, sex, primary site and size still showed no improvement in overall survival (RR 1.16, 95%CI: 0.88-1.54). Likewise, the extent of resection did not impact the effect of postoperative radiotherapy.