title: Cyclooxygenase-2 expression is associated with poor overall survival of patients with gastric cancer: a meta-analysis.
abstract: BACKGROUND
  Cyclooxygenase-2 (COX-2) is believed to be involved in gastric carcinogenesis. However, it is still controversial whether COX-2 expression can be regarded as a prognostic factor for gastric cancer patients.
  
  
  OBJECTIVE
  To obtain a more accurate relationship between COX-2 overexpression and prognosis in gastric cancer by meta-analysis.
  
  
  METHODS
  Relevant articles published up to May 2013 were searched by use of several keywords in electronic databases. Separate hazard ratio (HR) estimates and 95 % confidence intervals (95 % CI) for COX-2 overexpression and overall survival (OS) and disease-free survival (DFS) with gastric cancer were extracted. Combined HR with 95 % CI was calculated by use of Stata11.0 software to estimate the size of the effect. Publication bias testing and sensitivity analysis were also performed.
  
  
  RESULTS
  A total of 27 studies which included 3,891 gastric cancer patients were combined in the final analysis. Combined results suggested that COX-2 overexpression was associated with an unfavorable OS (HR 1.58, 95 % CI 1.36-1.84) but not DFS (HR 1.15, 95 % CI 0.93-1.43) among patients with gastric cancer. Publication bias was absent. Sensitivity analysis suggested that the results of this meta-analysis were robust.
  
  
  CONCLUSIONS
  The results of this meta-analysis suggest that high COX-2 expression may be an independent risk factor for poor OS of patients with gastric cancer. More large prospective studies are now needed to further clarify the prognostic value of COX-2 expression for DFS in gastric cancer.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, 69 Meishan Road, Hefei, 230032, Anhui Province, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Song
authors.forename: Hong
authors.initials: H
authors.lastname: Su
authors.forename: Yang-Yang
authors.initials: YY
authors.lastname: Zhou
authors.forename: Liang-Liang
authors.initials: LL
authors.lastname: Guo
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D016009:Chi-Square Distribution; D051546:Cyclooxygenase 2 / Q000032:analysis*; D018572:Disease-Free Survival; D006801:Humans; D053208:Kaplan-Meier Estimate; D016014:Linear Models; D015999:Multivariate Analysis; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000201:enzymology* / Q000401:mortality*; D013997:Time Factors; D015854:Up-Regulation
chemical_list: D014408:Biomarkers, Tumor; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human