Effect of re-irradiation at bevacizumab failure in recurrent glioblastoma: a comparative analysis with maintenance bevacizumab

Purpose Recurrent glioblastoma (GBM) is challenging, and effective treatment options after bevacizumab failure are limited. Re-irradiation combined with bevacizumab has emerged as a potential therapeutic option for recurrent GBM patients who have failed bevacizumab treatment. This study aims to evaluate the efficacy of re-irradiation in patients with progressive GBM refractory to bevacizumab monotherapy and explore the factors that may impact survival. Methods and materials This retrospective study enrolled 64 patients who developed a second progression after single-agent bevacizumab therapy. The patients were divided into two groups: 35 continued with bevacizumab alone (none-ReRT group), and 29 received bevacizumab and re-irradiation (ReRT group). The study measured overall survival time after bevacizumab failure (OST-BF) and after re-irradiation (OST-RT). Statistical tests were used to compare categorical variables, evaluate the difference in recurrence patterns between the two groups, and identify optimal cutoff points for re-irradiation volume. Results The Kaplan-Meier survival analysis revealed that the ReRT group had a significantly higher survival rate and longer median survival time than the none-ReRT group. The median OST-BF and OST-RT were 14.5 months and 8.8 months, respectively, for the ReRT group, while the OST-BF for the none-ReRT group was 3.9 months (p < 0.001). Cox univariate analysis for overall survival time after bevacizumab failure (OST-BF) identified KPS at bevacizumab failure, ORR, bevacizumab failure pattern, re-irradiation, and re-irradiation target volume as significant predictors of survival time after bevacizumab failure. The multivariable analysis found only the re-irradiation target volume to be significant for OST-RT. Conclusions The study suggests that re-irradiation combined with bevacizumab therapy may be a valuable treatment option for patients with recurrent GBM who have failed bevacizumab therapy. The re-irradiation target volume may be a valuable prognostic factor for these patients, with smaller target volumes associated with better survival outcomes. Further studies with larger sample sizes and prospective designs are necessary to confirm these results and determine the optimal treatment approach for these patients.