S363
Clinical - CNS
ESTRO 2026
Netherlands. 6 Department of Radiation Oncology, Catharina Hospital, Eindhoven, Netherlands. 7 Department of Radiation Oncology, Instituut Verbeeten, Tilburg, Netherlands. 8 Department of Radiation Oncology, Isala Clinics, Zwolle, Netherlands. 9 Department of Neurology, Leiden UMC, Leiden, Netherlands. 10 Department of Neurology, Medisch Spectrum Twente, Enschede, Netherlands. 11 Department of Radiology, UMC Utrecht, Utrecht, Netherlands. 12 Department of Medical Oncology, UMC Utrecht, Utrecht, Netherlands Purpose/Objective: Glioblastoma remains the most aggressive primary brain tumor in adults, with limited survival. New, shorter radiotherapy (RT) schedules might provide non-inferior survival compared to the standard Stupp- protocol, resulting in less burden to the patient [1-2]. This is the goal of the GOLD, multicenter RCT in the Netherlands (trial-ID: NL72953.041.20). Beyond classical endpoints, such as overall survival (OS), radiological signals, particularly trajectories of tumor changes, carry crucial information about treatment effects, progression and others. The aim of this work is to analyze the longitudinal evolution of tumor-related MRI changes after RT comparing hypofractionated (6x6Gy, interventional arm) versus standard chemoradiation (30x2Gy, control arm). Material/Methods: While the RCT is multicenter, current work focuses on patients participated in UMC Utrecht, 57 in total. MRIs were considered until progression or death, resulting in a total number of 300 timepoints. High - resolution (1 mm ³ isotropic) MRIs were coregistered to subject - specific templates via FreeSurfer to limit interpolation bias [3]. Then, we used an nnU - Net- based [4] tool to segment resection cavity, contrast - enhancing tissue, and peritumoral edema using T1w MRI with (T1Gd) and without contrast agent (T1), and T2 - FLAIR. Longitudinal measurements were analyzed using linear mixed-effects models to account for repeated measurements within patients and irregular timing of follow-up assessments. Fixed effects included treatment group, time, and their interaction; estimated marginal means with Kenward– Roger approximation yielded group differences over time, with 95% CIs used to demarcate significant
or flare of pre-existing symptoms. Median decrease in random normetadrenaline post SRS was 30.2% (10.9- 56.7%) among secretory tumours. There were no Common Terminology Criteria for Adverse Events (CTCAE) Grade 3 or higher toxicities. Regarding functional outcomes, 11.5% had complete resolution, 42.3% experienced partial improvement, 46.2% remained stable and no patient had worse pre-existing or new symptoms. On multivariate analysis, age appeared to significantly influence the likelihood of symptom improvement following SRS (p = 0.023). This finding was supported by a moderate Pearson correlation (r = 0.536, 95% CI 0.188–0.765; p = 0.005) indicating that younger age at the time of treatment was associated with a higher likelihood of symptom resolution. Conclusion: Five fraction SRS for SBPGLs provides a safe, effective, and well-tolerated treatment, ensuring symptom and biochemical stability without compromising cranial nerve function. References: 1. Lloyd S, Obholzer R, Tysome J; BSBS Consensus Group. British Skull Base Society Clinical Consensus Document on Management of Head and Neck Paragangliomas. Otolaryngol Head Neck Surg. 2020 Sep;163(3):400-4092. Fatima N, Pollom E, Soltys S, Chang SD, Meola A. Stereotactic radiosurgery for head and neck paragangliomas: a systematic review and meta-analysis. Neurosurg Rev. 2021 Apr;44(2):741-752 Keywords: paraganglioma, stereotactic radiosurgery, outcomes Longitudinal MRI assessment of glioblastoma response in the GOLD randomized trial of hypofractionated versus standard chemoradiation Szabolcs David 1,2 , Anouk M de Jong 1,3 , Arthur T. J. van der Boog 1,3 , Selena I. Huisman 2 , Gerda Wester 4 , Daniëlle B. P. Eekers 5 , Tom C. G. Budiharto 6 , Tom Rozema 7 , Mariska A. E. van de Sande 7 , Frank J. Lagerwaard 2 , Anna M. E. Bruynzeel 2 , Crystal de Groot 8 , Matthijs van der Meulen 9,10 , Fia Cialdella 1,3 , Jan-Willem Dankbaar 11 , Jeroen Hendrikse 11 , Karin E. Kleynen 1 , An Claes 1 , Marielle E. P. Philippens 1 , Ernst Smid 1 , Filip Y. F. L. de Vos 12 , Pierre A Robe 3 , Tom J. Snijders 3 , Joost J. C. Verhoeff 1,2 1 Department of Radiation Oncology, UMC Utrecht, Utrecht, Netherlands. 2 Department of Radiation Oncology, Amsterdam UMC, Amsterdam, Netherlands. 3 Department of Neurology and Neurosurgery, UMC Utrecht, Utrecht, Netherlands. 4 Department of Radiation Oncology, Radiotherapiegroep, Arnhem, Netherlands. 5 Department of Radiation Oncology, Maastricht University Medical Centre, Maastricht, Mini-Oral 1732
intervals. Results:
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