title: MGMT promoter methylation and glioblastoma prognosis: a systematic review and meta-analysis.
abstract: OBJECTIVE
  We undertook this study to comprehensively summarize the associations between MGMT promoter methylation and prognosis of glioblastoma (GBM).
  
  
  METHODS
  We searched PubMed, EMBASE and Cochrane databases (from January 2003 to November 1, 2011) and the references of the relevant articles in English with hazard ratios (HRs) and 95% confidence intervals (95% CIs). Two reviewers independently extracted data using a standardized form. Discrepancies were adjudicated by discussion.
  
  
  RESULTS
  Twenty four studies met the inclusion criteria. There were 22 studies reporting on the relationship between MGMT methylation and overall survival (OS) of GBM and 12 studies on the association between MGMT methylation and progression-free survival (PFS) of GBM. Patients with a methylated status of MGMT had significant OS and PFS advantage (HR = 0.48, 95% CI: 0.35-0.65; I² = 79.78 for OS; HR = 0.43, 95% CI: 0.32-0.56; I² = 50.38 for PFS). Pooled HRs remained significant in further subgroup analysis based on the year of publication and continents of studies.
  
  
  CONCLUSIONS
  Patients with MGMT promoter methylation had significant OS and PFS advantage than those without methylated status.
authors.affiliation: Department of Biotechnology, Dalian Medical University, Liaoning Province, Dalian, People's Republic of China. dlmuyangchen@126.com
authors.forename: Yang
authors.initials: Y
authors.lastname: Chen
authors.forename: Fulan
authors.initials: F
authors.lastname: Hu
authors.forename: Yiheng
authors.initials: Y
authors.lastname: Zhou
authors.forename: Wangyang
authors.initials: W
authors.lastname: Chen
authors.forename: Hongying
authors.initials: H
authors.lastname: Shao
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D001932:Brain Neoplasms / Q000175:diagnosis / Q000378:metabolism* / Q000401:mortality; D019175:DNA Methylation; D018572:Disease-Free Survival; D018740:Genetic Heterogeneity; D005909:Glioblastoma / Q000175:diagnosis / Q000378:metabolism* / Q000401:mortality; D006801:Humans; D008745:Methylation; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000235:genetics*; D011379:Prognosis; D011401:Promoter Regions, Genetic
chemical_list: D019853:O(6)-Methylguanine-DNA Methyltransferase