2610 - MR-Guided Adaptive Radiotherapy for Glioblastoma: Clinical Outcomes and Quality of Life in an Australian Cohort
Presenter(s)
K. E. Jamora1, M. Wada1, R. Khor1, H. Gan2, A. Gonzalvo3, L. Cher2, E. Lau4, M. Tacey1, G. Barjaktarovic5, S. Fisher1, F. Height1, A. Scott6, and S. P. Ng1; 1Department of Radiation Oncology, Austin Health, Melbourne, VIC, Australia, 2Department of Medical Oncology, Austin Health, Melbourne, VIC, Australia, 3Department of Neurosurgery, Austin Health, Melbourne, VIC, Australia, 4Department of Radiology, Austin Health, Melbourne, VIC, Australia, 5Department of Radiation Oncology, Townsville University Hospital, Townsville, QLD, Australia, 6Department of Molecular Imaging and Therapy, Austin Health, Melbourne, VIC, Australia
Purpose/Objective(s): The magnetic resonance linear accelerator (MRL) enables daily adaptation of radiation therapy plans. This study presents our institutional experience with the clinical outcomes and quality of life (QoL) of glioblastoma patients treated using a 1.5 Tesla (T) MRL.
Materials/Methods: We identified glioblastoma patients enrolled in a prospective registry (FIRM study) who were treated with MRL between August 2021 and May 2024. Acute toxicity was assessed until 19 weeks post-radiotherapy initiation. QoL was evaluated at baseline and at regular follow-ups using the EORTC QLQ-C30 and QLQ-BN20 questionnaires. Cumulative overall survival (OS) and progression-free survival (PFS) were estimated using Kaplan-Meier analysis.
Results: A total of 28 patients were included, with a median follow-up of 12.16 months (range 0.5–30.6 months). The mean age at registration was 63 years; 15 were male, and 27 had an ECOG performance status of 0-1. Eleven patients underwent gross total resection, 9 had subtotal resection, and 8 had biopsy only. All were IDH-wild type; 10 were MGMT-methylated, 16 non-methylated, and 2 had unknown status. Concurrent temozolomide was administered to 25 patients. This was the first radiation course for 25 patients, while 3 received re-irradiation at the same primary site. Sixteen patients (57.1%) were treated with 60 Gy in 30 fractions, 11 (39.3%) with 40 Gy in 15 fractions, and one (3.6%) with 26 Gy in 13 fractions. The mean interval from CT/MRI simulation to radiotherapy start was 12.6 days. One patient received one fraction on a conventional linear accelerator due to technical issues, while the remaining 27 patients completed all prescribed fractions on the MRL. The mean in-room time per fraction was 39.4 minutes (range: 33.2–56.5 minutes). Twelve patients (42.9%) required Adapt-To-Shape or re-planning within the first week due to tumor progression, indicated by increased T2/FLAIR signal beyond the initial CTV on daily MRL imaging. Acute grade 2 fatigue occurred in 6 patients (21%), and no grade 3-4 toxicities were reported. At 3 months, treatment was associated with declines in QLQ-C30 global health status, physical and cognitive functioning, and worsening pain, with most domains returning to baseline by 6 months. BN-20 assessments showed worsening communication deficits and visual disorders at 3 and 6 months, with improvements in future uncertainty at 6 months. The median OS and PFS were 13.6 and 9.5 months, respectively.
Conclusion: Treatment of glioblastoma with MR-guided adaptive radiotherapy is feasible, with manageable acute toxicities and adaptive capabilities to address tumor changes.