Identifying the optimal cutoff point for MGMT promoter methylation status in glioblastoma
Ngan Nguyen,
Jordan Redfield,
Matthew Ballo,
Madison Michael,
Jeffrey Sorenson,
Daniel Dibaba,
Jim Wan,
Glenda Delgado Ramos,
Manjari Pandey
Affiliations
Ngan Nguyen
1University of Tennessee Health Science Center, Memphis, TN 38163, USA
Jordan Redfield
1University of Tennessee Health Science Center, Memphis, TN 38163, USA
Matthew Ballo
2Deparment of Radiation Oncology, West Cancer Center & Research Institute, Memphis, TN 38138, USA
Madison Michael
3Department of Neurosurgery at University of Tennessee Health Science Center & Semmes Murphey Clinic, Memphis, TN 38163, USA
Jeffrey Sorenson
3Department of Neurosurgery at University of Tennessee Health Science Center & Semmes Murphey Clinic, Memphis, TN 38163, USA
Daniel Dibaba
4University of Tennessee Health Science Center, Tennessee Clinical & Translational Science Institute, Memphis, TN 38163, USA
Jim Wan
4University of Tennessee Health Science Center, Tennessee Clinical & Translational Science Institute, Memphis, TN 38163, USA
Glenda Delgado Ramos
5Loyola University Medical Center, Maywood, IL 60153, USA
Manjari Pandey
6Department of Hematology and Oncology, University of Tennessee Health Science Center & West Cancer Center & Research Institute, Memphis, TN 38138, USA
Aim: To define the optimal cutoff point for determining methylation status of O6-methylguanine-DNA methyltransferase (MGMT) by pyrosequencing in glioblastoma. Patients & methods: A retrospective study of 109 glioblastoma patients was performed to determine the optimal cutoff point for MGMT methylation status. Results: Receiver operating characteristic (ROC) analysis revealed 21% as the optimal cutoff (sensitivity: 68%; specificity: 59%) for MGMT methylation corresponding with the highest likelihood ratio of 1.66 and accuracy of 0.65. Methylation status (hazard ratio: 0.453; 95% CI: 0.279–0.735; p = 0.001) was associated with better overall survival. The crude model indicated linearity between methylation percent and survival rate; an increase of 10% of methylation resulted in a reduction of risk of death by 20% (p = 0.004). Conclusion: ROC analysis determined 21% as the optimal cutoff point for MGMT methylation status by pyrosequencing.
