ESTRO 2024 - Abstract Book

S879

Clinical - CNS

ESTRO 2024

reveal an association of granular MGMT methylation percentage with outcome within the unmethylated group and between DDR-related gene expression signatures and overall survival across the study population.

Keywords: Glioblastoma, radiosensitiser, PARP inhibitor

1979

Digital Poster

Predicting radionecrosis following different radiotherapy dose for intracranial meningiomas

Martin Palička 1 , Anouk M. de Jong 2 , Szabolcs Dávid 2 , Marian Rybář 3 , Jana Jackaninová 1 , Lukáš Knybel 1 , Štefan Reguli 4 , Tomáš Blažek 1 , Joost J.C. Verhoeff 2 , Jakub Cvek 1 1 University Hospital Ostrava, Oncology, Ostrava, Czech Republic. 2 UMC Utrecht, Radiotherapy, Utrecht, Netherlands. 3 Czech Technical University, Computing and Information Centre, Prague, Czech Republic. 4 University Hospital Ostrava, Neurosurgery, Ostrava, Czech Republic

Purpose/Objective:

Radiotherapy (RT) is a feasible alternative to surgery for intracranial meningeomas. Reported studies of stereotactic RT utilized single fraction radiosurgery, fractionated stereotactic or conventional radiotherapy. The goal of this retrospective analysis was to compare toxicity in a large international cohort.

Material/Methods:

Between 2010 and 2021, a total of 473 consecutive patients were treated for intracranial meningioma at two radiation oncology clinics. The patients underwent treatment modalities including stereotactic radiosurgery (SRS), hypofractionated RT (hFSRT), or normofractionated RT (nFSRT) using CT-linac or Cyberknife radiation techniques. Post-treatment, the patients were monitored radiologically in line with clinic protocols. Only patients with a follow up duration of at least 6 months were considered for the analysis. The evaluation of potential edema and/or radionecrosis was conducted through MR images, focusing especially on T1 3D contrast-enhanced and T2 or T2 with fluid attenuation (FLAIR) series.

Results:

In the analyzed sample, 11.0 % of patients experienced radiation-induced brain edema, and a total of 4.0 % of patients developed radionecrosis. Asymptomatic edema occurred in 6.1 % of patients, while symptomatic edema was observed in 4.9 % of patients. The median time to the development of brain edema and radionecrosis was 8.6 and 10.9 months, respectively. Despite a smaller irradiated tumor volume the risk of radiation-related toxicity increased with SRS compared to hFSRT and nFSRT both for brain edema (HR = 4.10, CI 0.95 = (2.02; 8.26), p < 0.001), and radionecrosis (HR = 11.07, CI 0.95 = (2.65; 46.24), p < 0.001). Cox regression analysis showed increasing risk of