Figure 2. Recursive Partitioning Analysis (RPA) for Post-2005/IDH-Known Subset.

Includes 434 patients. Four risk groups were determined by RPA based on adjuvant temozolomide treatment after surgery, isocitrate dehydrogenase gene 1 or 2 (IDH) status, age at diagnosis, and residual non–contrast-enhancing (NCE) tumor after surgery. Groups are denoted by numbers 1 through 4. Group 4 is the combination of 2 subgroups: temozolomide-treated patients with IDH-mutant tumors and temozolomide-treated patients aged 65 years or younger with IDH–wild-type tumors with no greater than 5.4 mL of NCE residual tumor.