MGMT and cholesteryl ester measurement: Multivariable Cox proportional hazards regression analysis stratified for MGMT methylation status and risk adjusted for age ≤ 65y (HR 0.63; 95% CI, 0.49–0.81; p < 0.0001), KPS > 70 (HR 0.92; 95% CI, 0.71–1.19; p = 0.545), adjuvant chemoradiation (HR 0.13; 95% CI, 0.09–0.19; p < 0.0001), and smaller pre-operative CE tumor volumes per cm3 (HR 0.85; 95% CI, 0.75–0.95; p = 0.007) identified maximal CE tumor resection (HR 0.58; 95% CI, 0.39–0.87; p = 0.009) and ≥30% NCE tumor resection (HR 0.71; 95% CI, 0.53–0.93; p = 0.014) as being associated with longer overall survival (Table 2).