Radiotherapy versus combination radiotherapy-bevacizumab for the treatment of recurrent high-grade glioma: a systematic review

Background High-grade gliomas (HGG) comprise the most common primary adult brain cancers and universally recur. Combination of re-irradiation therapy (reRT) and bevacizumab (BVZ) therapy for recurrent HGG is common, but its reported efficacy is mixed. Objective To assess clinical outcomes after reRT +/- BVZ in recurrent HGG patients receiving stereotactic radiosurgery (SRS), hypofractionated radiosurgery (HFSRT), or fully fractionated radiotherapy (FFRT). Methods We performed a systematic review of PubMed, Web of Science, Scopus, Embase, and Cochrane databases, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We identified studies reporting outcomes for patients with recurrent HGG treated via reRT +/- BVZ. Cohorts were stratified by BVZ treatment status and re-irradiation modality (SRS, HFSRT, and FFRT). Outcome variables were overall survival (OS), progression-free survival (PFS), and radiation necrosis (RN). Results Data on 1399 patients was analyzed, with 954 patients receiving reRT alone and 445 patients receiving reRT + BVZ. All patients initially underwent standard-of-care therapy for their primary HGG. In a multivariate analysis that adjusted for median patient age, WHO grade, RT dosing, reRT fractionation regimen, time between primary and re-irradiation, and re-irradiation target volume, BVZ therapy was associated with significantly improved OS (2.51, 95% CI [0.11, 4.92] months, P = .041) but no significant improvement in PFS (1.40, 95% CI [- 0.36, 3.18] months, P = .099). Patients receiving BVZ also had significantly lower rates of RN (2.2% vs 6.5%, P < .001). Conclusions Combination of reRT + BVZ may improve OS and reduce RN rates in recurrent HGG, but further controlled studies are needed to confirm these effects.