ESTRO 2025 - Abstract Book

S745

Clinical - CNS

ESTRO 2025

Results:

Eighty-three patients (63.9% male, median age 60 years) were included, 21 of whom underwent re-irradiation. MGMT promoter methylation was detected in 71.8% of cases. Among re-irradiated patients, 57.9% had a Gross Total Resection after the second surgery, compared to 48.1% of non-re-irradiated patients (p=NS). Recurrence occurred in-field in 81% of re-irradiated patients, versus 93.2% in the surgical cavity for non-re-irradiated patients (p=NS). Adjuvant therapy after re-surgery significantly improved OS and PFS (p<0.0001). Comparing approaches (Wait and See, second-line chemotherapy, and the combined approach of re-irradiation with second-line chemotherapy), the combined approach significantly improved OS (p<0.001) (Fig 1-2). Multivariate analysis showed that combining re-irradiation with systemic therapy and a third surgery significantly influenced PFS at 6 months and OS at 6 and 12 months.

Conclusion: In the absence of a standard for recurrent GBM treatment, this study highlights the role of adjuvant therapies, particularly re-irradiation after re-surgery. Despite the limitations of this retrospective analysis, the small patient cohort, re-irradiation combined with systemic therapy emerged as an effective strategy, significantly improving OS and PFS. These findings underscore the potential of re-irradiation to enhance outcomes in recurrent GBM, offering a meaningful option for patients in this challenging clinical scenario.

Keywords: Reirradiation, Glioblastoma , Combined treatments