Significance of O6-methyl Guanine Methyltransferase Promoter Methylation in High Grade Glioma Patients: Optimal Cutoff Point, CpG Locus, and Genetic Assay

To evaluate O6-methyl guanine methyltransferase (MGMT) promoter methylation status in high grade glioma patients and to identify the best cutoff point as well as the most predictive CpG loci for patients survival. Consecutive high grade glioma patients treated with surgical gross total resection followed by concomitant radiochemotherapy and adjuvant chemotherapy were included in this retrospective observational study. Methylation status of MGMT promoter CpG island of resected tumor tissue were evaluated using next generation sequencing assay. The outcomes were grouped as CpG 70–78, CpG 79–83, CpG 84–87, CpG 70–87, and whole promoter. Quantitative analyses were dichotomized as methylated or unmethylated based on the cutoff points set to