Kaplan–Meier survival curves based on classification by (A) c.-56C > T SNP genotype for the AGOG cohort, (B) interaction between the c.-56C > T SNP genotype and MGMT methylation assessed by pyrosequencing for the AGOG cohort, (C) c.-56C > T SNP genotype for the UCLA/KPLA cohort, and (D) interaction between the c.-56C > T SNP genotype and MGMT methylation assessed by MSP for the UCLA/KPLA cohort. Abbreviations: Meth, methylation of the MGMT promoter; Non-meth, nonmethylated MGMT promoter; T, variant T allele of the SNP rs16906252; C, wild-type C allele.