Retrospective study of re-irradiation for high-grade glioma: prognostic factors and predictors of radiation necrosis

The optimal patient selection for re-irradiation (re-RT) among patients with recurrent high-grade glioma (rHGG) is not yet clear. A retrospective study at the University of Toronto (Canada) identified prognostic factors for rHGG patients treated with re-RT. The median overall survival after re-RT was 9.9 months (95% CI 8.3-11.6). Among the factors associated with improved OS were re-resection at progression, longer interval from primary treatment to first progression, longer interval from primary treatment to re-RT, and smaller re-RT PTV volume. Patients who had unmethylated-MGMT tumors, 3 or more lines prior systemic treatment were more likely to die within 6 months of re-RT. The cumulative incidence of radiation necrosis was 11.4% at 12 months. Concurrent bevacizumab mitigated the risk of RN.