ESTRO 2025 - Abstract Book

S766

Clinical - CNS

ESTRO 2025

4482

Digital Poster Does IDH-Mutant Astrocytoma have a better prognosis Than Glioblastoma? sirine zouari, Zelaiti hajer, trigui rim, siala wicem, fourati nejla, daoud jamel Habib Bourguiba University hospital, Radiation oncology, sfax, Tunisia

Purpose/Objective: Advances in the molecular classification of central nervous system (CNS) tumors, particularly with the 2021 WHO classification, have highlighted the significance of IDH mutation status. Patients with grade 4 IDH-mutant astrocytomas have demonstrated improved progression-free and overall survival compared to those with glioblastoma (IDH-wild type). The aim of this study is to evaluate and compare the prognosis between these two patient groups. Material/Methods: This retrospective study included 50 patients, 34 with glioblastoma (68%) and 16 with grade 4 astrocytoma (32%), treated between January 2021 and April 2024. Kaplan-Meier analysis was used to evaluate local recurrence-free survival (DFS) and overall survival (OS). Results: The median age was 60 years [29-79] for glioblastoma patients and 53 years [36-77] for astrocytoma patients. The left temporal lobe was the most common tumor site in both groups, affecting 12 patients (24%). The median tumor diameter was 54.5 mm [24-89] for glioblastoma and 47.5 mm [22-80] for astrocytoma. All patients underwent surgery, with complete resection achieved in 24 (48%)—17 glioblastoma and 7 astrocytoma patients. Radiotherapy was administered to 25 patients (50%), including 15 glioblastoma and 10 astrocytoma patients. Only grade 4 astrocytoma patients received adjuvant chemotherapy with Temozolomide. Tumor recurrence occurred in 28 glioblastoma patients (82%) and 13 astrocytoma patients (81%). Of those with recurrence, 9 patients were treated, with surgery being the primary approach for 7 patients. The median DFS was 4 months (range: 1-38) for glioblastoma patients and 7 months (range: 1-20) for astrocytoma patients (p=0.5). Median OS was 6 months (range: 2-38) for glioblastoma and 14 months (range: 2-26) for astrocytoma (p=0.044). Conclusion: Our findings suggest that IDH-mutant grade 4 astrocytomas are associated with a more favorable OS compared to glioblastoma, highlighting the potential importance of IDH mutation status in prognosis. However, given the retrospective nature of this study, these results should be interpreted with caution. Further validation through well designed, prospective trials is necessary to confirm these findings and to better understand the role of IDH mutation in treatment outcomes.

Keywords: Glioblastoma, IDH-mutant type, IDH-wild type