Pulsed Reduced Dose Rate Radiotherapy in Conjunction With Bevacizumab or Bevacizumab Alone in Recurrent High-grade Glioma: Survival Outcomes

PURPOSE: Dismal prognosis and limited treatment options for recurrent high-grade glioma have provoked interest in various forms of reirradiation. Pulsed reduced dose rate radiation therapy (pRDR) is a promising technique that exploits low-dose hyper-radiosensitivity of proliferating tumor cells while sparing adjacent nonproliferating normal brain tissue. Large radiation treatment volumes can thus be used to target both contrast-enhancing and FLAIR abnormalities thought to harbor recurrent gross and microscopic disease, respectively. The aim of this retrospective study was to determine whether the addition of pRDR to bevacizumab improves survival over bevacizumab alone for recurrent high-grade glioma. METHODS AND MATERIALS: Eighty patients with recurrent high-grade glioma were included in this study; 47 patients received bevacizumab monotherapy (BEV), and 33 patients received pRDR with bevacizumab (BEV/pRDR). Progression-free survival (PFS) and overall survival were compared between the BEV and BEV/pRDR groups. Regression analysis was performed to identify and control for confounding influences on survival analyses. RESULTS: Significant (P <.05) advantages in PFS (12 vs 4 months; hazard ratio = 2.37) and OS (16 vs. 9 months; hazard ratio = 1.68) were observed with BEV/pRDR compared with BEV alone. CONCLUSIONS: This retrospective analysis suggests that treatment with pRDR in addition to bevacizumab could significantly prolong PFS and overall survival compared with bevacizumab alone for recurrent high-grade glioma.