S387
Clinical - CNS
ESTRO 2026
2023. Independent prognostic factors were identified using multivariate Cox proportional hazards analysis. A prognostic score was then constructed by assigning integer values proportional to the hazard ratios, and its discriminative performance was evaluated using time-dependent concordance indices (C-index). Results: The median follow-up was 18 months, and the median overall survival (OS) was 21 months, with a 1-year survival rate of 78.7%. Multivariate analysis identified MGMT unmethylation (HR = 2.64, p < 0.01), postoperative Karnofsky Performance Status (KPS ≤ 60; HR = 3.74, p < 0.01), and gross tumor volume (GTV ≥ 15 cc; HR = 2.24, p = 0.01) as independent prognostic factors. Based on these, the scoring model assigned: MGMT unmethylated = 2 points; postoperative KPS ≤ 60 = 3 points, 70–80 = 1 point, ≥ 90 = 0 points; GTV ≥ 15 cc = 1 point. Patients were stratified into low- ( ≤ 1 point, n = 26), intermediate- (2–4 points, n = 79), and high-risk ( ≥ 5 points, n = 12) groups. Median OS was 43, 19, and 11 months, respectively (log-rank p < 0.01). One-year survival rates were 92.3%, 81.4%, and 28.1%, and 3-year survival rates were 57.2%, 27.1%, and 0% Fig. 1. The overall C-index was 0.715, with time- specific C-indices of 0.83, 0.86, 0.75, 0.73, and 0.71 at 3, 6, 12, 24, and 60 months, maintaining ≥ 0.70 throughout. The Kaplan-Meier curves for the three risk groups are presented in Figure 1.
Conclusion: LRT appears to be a feasible therapeutic option in recurrent large HGG with a short but notable improvement in survival. Comprehensive research involving a large patient cohort is required, and further investigation into the combination of LRT and immunotherapies is recommended. Keywords: Glial tumors, Lattice radiation therapy Digital Poster 3892 A Simplified Three-Factor Prognostic Score for IDH- Wildtype Glioblastoma in the Molecular Era Akihito Okubo, Kenta Nishimura, Minamikawa Risako, Takayuki Sakurai, Shigeyuki Takamatsu, Satoshi Kobayashi Department of Radiology, Kanazawa university hospital, Ishikawa, Japan Purpose/Objective: Prognostication of glioblastoma survival has become more refined following the molecular reclassification of these tumors into isocitrate dehydrogenase (IDH) wild-type and IDH-mutant subtypes. However, robust and clinically practical prediction models applicable to the entire IDH-wildtype glioblastoma population remain limited. This study aimed to develop and validate a simple, yet reliable prognostic scoring system tailored to patients with IDH-wildtype glioblastoma in the contemporary molecular era. Material/Methods: We retrospectively analyzed 117 patients with newly diagnosed IDH1 R132H–negative glioblastoma and known O6-methylguanine DNA methyltransferase (MGMT) promoter methylation status, selected from 242 malignant glioma cases treated with postoperative radiotherapy between January 2008 and December
Conclusion: This three-factor prognostic score incorporating MGMT methylation status, postoperative KPS, and GTV enables clear and clinically meaningful stratification of patients with IDH-wildtype glioblastoma, showing stable discriminative performance across both short- and long-term survival intervals. References: 1. Whitfield BT, Huse JT. Classification of adult-type diffuse gliomas: Impact of the World Health Organization 2021 update. Brain Pathol. 2022
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