Survival benefits of hypofractionated radiotherapy combined with temozolomide or temozolomide plus bevacizumab in elderly patients with glioblastoma aged ≥ 75 years

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the outcomes of elderly patients (aged ≥75 years) with newly diagnosed glioblastoma (GBM), who were treated with hypofractionated radiotherapy comprising 45 Gy in 15 fractions combined with temozolomide (TMZ) or TMZ and bevacizumab (TMZ/Bev). MATERIALS AND METHODS: Between October 2007 and August 2018, 30 patients with GBM aged ≥75 years were treated with hypofractionated radiotherapy consisting of 45 Gy in 15 fractions. Twenty patients received TMZ and 10 received TMZ/Bev as upfront chemotherapy. O-6-methylguanine DNA methyltransferase (MGMT) promoter methylation status was analyzed by pyrosequencing. The cutoff value of the mean level of methylation at the 16 CpG sites was 16%. RESULTS: Median overall survival (OS) and progression-free survival (PFS) were 12.9 months and 9.9 months, respectively. The 1-year OS and PFS rates were 64.7 and 34.7%, respectively. Median OS and PFS did not differ significantly between patients with MGMT promoter hypermethylation (N = 11) and those with hypomethylation (N = 16) (17.4 vs. 11.8 months, p = 0.32; and 13.1 vs. 7.3 months, p = 0.11, respectively). The median OS and PFS were not significantly different between TMZ (N = 20) and TMZ/Bev (N = 10) chemotherapy (median OS: TMZ 12.9 months vs. TMZ/Bev 14.6 months, p = 0.93, median PFS: TMZ 8.5 months vs TMZ/Bev 10.0 months, p = 0.64, respectively). The median time until Karnofsky performance status (KPS) score decreasing below 60 points was 7.9 months. The best radiological responses included 11 patients with a partial response (36.7%). Grade 3/4 toxicities included leukopenia in 15 patients (50%), anorexia in 4 (13.3%), and hyponatremia during concomitant chemotherapy in 3 (10%). CONCLUSION: Our hypofractionated radiotherapy regimen combined with TMZ or TMZ/Bev showed benefits in terms of OS, PFS, and KPS maintenance with acceptable toxicities in elderly patients with GBM aged ≥75 years.