ESTRO 2025 - Abstract Book

S659

Clinical - CNS

ESTRO 2025

patients were diagnosed during their second or third recurrence, and MGMT unmethylated status was identified in 50% of patients. The study met its primary endpoint, showing a statistically significant improvement in the one-year survival rate compared to the EF-11 trial. The one-year overall survival (OS) rate was 67.5% versus 20% in controls, and the two year survival rate was 45% versus 17% (p=0.007). After propensity matching, these differences remained significant. The median OS (mOS) from recurrence for all patients was 16 months compared to 10 months in controls, and 25 months versus 9 months in the first recurrence subgroup. Radiation necrosis was observed in 20% of patients, but symptomatic (grade ≥2) necrosis occurred in only one case. Conclusion: The TaRrGeT trial met its primary endpoint, demonstrating that FET-PET-guided SRS combined with TTFields is a well-tolerated and effective treatment option for recurrent glioblastoma. The rate of symptomatic radiation necrosis was low, and survival outcomes significantly exceeded expectations, with notable improvements in one- and two year survival rates. These findings highlight the potential of this combined approach in managing recurrent glioblastoma. Digital Poster Survival advantage of Boron Neutron Capture Therapy in recurrent glioblastoma: A propensity-matched analysis Shuo-Fu Chen 1 , Yi-Yen Lee 2,3 , Sanford P. C. Hsu 2,3 , Feng-Chi Chang 4,3 , Shih-Chieh Lin 5 , Ko-Han Lin 6 , Jia-Cheng Lee 1,7 , Fong-In Chou 8 , Yi-Wei Chen 1,7,3 1 Heavy Particles & Radiation Oncology, Taipei Veterans General Hospital, Taipei, Taiwan. 2 Neurosurgery, Taipei Veterans General Hospital, Taipei, Taiwan. 3 School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan. 4 Radiology, Taipei Veterans General Hospital, Taipei, Taiwan. 5 Pathology and Laboratory Medicine, Taipei Veterans General Hospital, Taipei, Taiwan. 6 Nuclear Medicine, Taipei Veterans General Hospital, Taipei, Taiwan. 7 Medical Imaging and Radiological Technology, Yuanpei University of Medical Technology, Hsinchu, Taiwan. 8 Nuclear Science & Technology Development Department, National Tsing-Hua University, Hsinchu, Taiwan Purpose/Objective: Boron neutron capture therapy (BNCT) provides a targeted treatment for recurrent glioblastoma [1,2]; however, no studies have compared the survival outcomes between BNCT-treated patients and those who were not. This study aims to assess the survival benefits of BNCT in recurrent glioblastoma. Material/Methods: Adult patients with recurrent supratentorial glioblastoma who received standard first-line treatment between January 2015 and May 2023 were retrospectively analyzed. Patients were divided into two groups based on salvage treatment: the control group received bevacizumab ± chemotherapy, and the BNCT group received additional BNCT. BNCT was performed through intravenous administration of L-(4- 10 Borophenyl) alanine (L- 10 BPA) as the boron carrier, followed by neutron irradiation using the Tsing Hua Open-Pool Reactor. A mean target dose of 20 to 40 Gy-Equivalent was prescribed. To minimize confounders, we applied 1:1 propensity score matching based on age, performance status, and the proportion of patients who underwent re-resection and chemotherapy. Landmark analysis and Cox regression with BNCT initiation as a time-dependent covariate were performed to address immortal time bias. Keywords: Glioma, Re-irradiation, SRS 545

Results: A total of 135 IDH wild-type patients were included in our analysis, with 89 in the control group and 46 in the BNCT