A meta-analysis of temozolomide versus radiotherapy in elderly glioblastoma patients

Abstract

Temozolomide (TMZ) alone has been proposed as a promising alternative to radiotherapy (RT) in elderly glioblastoma (GBM) patients. We report a meta-analysis to systematically evaluate TMZ monotherapy in older GBM patients. A systematic literature search was performed using PubMed, EMBASE and the Cochrane database. Studies comparing TMZ versus RT in elderly patients (≥ 65 years) with newly diagnosed GBM were eligible for inclusion. Two randomized clinical trials (RCTs) and three comparative studies were included in the analyses, which revealed an overall survival (OS) advantage for TMZ compared with RT (HR [hazard ratio] 0.86, 95 % CI [confidence interval] 0.74-1.00). However, a sensitivity analysis of 2 RCTs only supported its non-inferiority (HR 0.91, 95 % CI 0.66-1.27). Most elderly patients tolerated TMZ despite an increased risk of grade 3-4 (G3-4) toxicities, especially hematological toxicities. The quality of life was similar between the groups. In the MGMT analysis, methylated tumors were associated with a longer OS than unmethylated tumors among elderly patients receiving TMZ monotherapy (HR 0.50, 95 % CI 0.35-0.70). Moreover, in patients with methylated tumors, TMZ was more beneficial than RT alone in improving OS (TMZ vs. RT: HR 0.66, 95 % CI 0.47-0.93) whereas the opposite was true for those with unmethylated tumors (HR 1.32, 95 % CI 1.00-1.76). Although the meta-analysis demonstrated the non-inferiority to RT in improving OS, TMZ alone was not a straightforward solution for elderly GBM patients because of an increased risk of G3-4 toxicities, especially hematological toxicities. MGMT testing might be helpful for determining individualized treatment.