MGMT and neoplasm: Overall survival, defined from last tumor-directed surgery to death or last follow-up, was analyzed using Kaplan-Meier methods and Cox proportional hazards regression adjusted for age, sex, preoperative Karnofsky Performance Status, surgery type, postoperative treatment, isocitrate dehydrogenase mutation status, and O6-methylguanine-DNA methyltransferase promoter methylation status.