title: GSTM1 and GSTT1 polymorphisms and nasopharyngeal cancer risk: an evidence-based meta-analysis.
abstract: BACKGROUND
  Previous evidence implicates polymorphisms of GSTM1 and GSTT1, candidates of phase II enzymes, as risk factors for various cancers. A number of studies have conducted on the association of GSTM1 and GSTT1 polymorphism with susceptibility to nasopharyngeal carcinoma (NPC). However, inconsistent and inconclusive results have been obtained. In the present study, we aimed to assess the possible associations of NPC risk with GSTM1 and GSTM1 null genotype, respectively.
  
  
  METHODS
  The associated literature was acquired through deliberate searching and selected based on the established inclusion criteria for publications, then the extracted data were further analyzed using systematic meta-analyses.
  
  
  RESULTS
  A total of 85 articles were identified, of which eight case-control studies concerning NPC were selected. The results showed that the overall OR was 1.42 (95%CI = 1.21-1.66) for GSTM1 polymorphism. While for GSTT1 polymorphism, the overall OR was 1.12 (95% CI = 0.93-1.34).
  
  
  CONCLUSIONS
  The data were proven stable via sensitivity analyses. The results suggest GSTM1 deletion as a risk factor for NPC and failed to suggest a marked correlation of GSTT1 polymorphisms with NPC risk.
authors.affiliation: Department of Otolaryngology, Southwest Hospital, Third Military Medical University, Chongqing, PR China. zhuoxianlu@yahoo.com
authors.forename: Xianlu
authors.initials: X
authors.lastname: Zhuo
authors.forename: Lei
authors.initials: L
authors.lastname: Cai
authors.forename: Zhaolan
authors.initials: Z
authors.lastname: Xiang
authors.forename: Qi
authors.initials: Q
authors.lastname: Li
authors.forename: Xueyuan
authors.initials: X
authors.lastname: Zhang