Meta-analysis of alkylating chemoradiotherapy versus radiotherapy only in IDH-wildtype and IDH-mutant grade 2 and 3 gliomas

Meta-analysis of six randomized trials with 1,204 patients with grade 2 or 3 glioma (430 IDH-wildtype; 774 IDH mutant) evaluated addition of alkylating chemotherapy to radiotherapy. Among patients with IDH-wildtype tumors, addition of alkylating chemotherapy to radiotherapy was associated with improved progression-free survival (HR 0.77; p=0.03) but not overall survival (HR 0.87; p=0.17). Among patients with IDH-mutant tumors, addition of alkylating chemotherapy to radiotherapy was associated with improved progression-free survival (HR 0.47; p<0.001) and overall survival (HR 0.52; p<0.001). Magnitude of benefit was similar for IDH-mutant gliomas with or without 1p19q-codeletion. The authors conclude that optimal management of IDH-wildtype lower grade gliomas remain to be determined, as there is little evidence supporting an overall survival benefit from alkylating chemotherapy (graphical abstract).