title: Association of GSTP1 Ile105Val polymorphism with risk of esophageal cancer: a meta-analysis of 21 case-control studies.
abstract: BACKGROUND
  The association of glutathione s-transferase P1 (GSTP1) Ile105Val polymorphism with risk of esophageal cancer (EC) has been evaluated in many studies; however, the results from these studies are controversial. Thus, further analysis on association between GSTP1 Ile105Val polymorphism and risk of EC is needed among a larger study population.
  
  
  METHODS
  We searched the relevant electronic databases and performed a meta-analysis based on 21 published case-control studies. The Chi-square based I(2)-statistic test was performed to evaluate possible heterogeneity across the studies. Additionally, random-effects models were used to calculate crude pooled odds ratios (ORs) with 95% confidence intervals (CIs).
  
  
  RESULTS
  Overall, this meta-analysis did support a significant association between GSTP1 Ile105Val polymorphism and risk of EC (pooled OR 1.25, 95% CI, 1.05-1.49). Furthermore, the stratified analysis showed that, in comparison to GSTP1 Ile105Val Ile/Ile genotype, the Val/Val genotype was significantly associated with risk of esophageal squamous cell carcinoma (ESCC) (pooled OR 1.45, 95% CI, 1.07-1.96), particularly in the Caucasian population (pooled OR 1.41, 95% CI, 1.01-1.95). Such a significant association was not observed for esophageal adenocarcinoma (EAC) patients or subjects of an Asian ethnicity. Moreover, substantial evidence of heterogeneity among the studies was not observed.
  
  
  CONCLUSIONS
  The results from this meta-analysis support a significant association between the GSTP1 Ile105Val polymorphism and risk of EC, particularly in a subgroup with ESCC and in the Caucasian population. Further studies with larger sample sizes are needed to validate our findings.
authors.affiliation: Department of Radiation Oncology, Affiliated Yantai Yuhuangding Hospital, Qingdao University Yantai 264000, China.
authors.forename: Yipeng
authors.initials: Y
authors.lastname: Song
authors.affiliation: Department of Radiation Oncology, Affiliated Yantai Yuhuangding Hospital, Qingdao University Yantai 264000, China.
authors.forename: Yuanna
authors.initials: Y
authors.lastname: Du
authors.affiliation: Department of Tumor Biological Treatment, The Third Affiliated Hospital, Soochow University Changzhou 213003, Jiangsu Province, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: Department of Radiation Oncology, Affiliated Yantai Yuhuangding Hospital, Qingdao University Yantai 264000, China.
authors.forename: Jinbo
authors.initials: J
authors.lastname: Ma
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital Jinan 250012, Shandong, China.
authors.forename: Jinming
authors.initials: J
authors.lastname: Yu
authors.affiliation: Radiology Department of Shanghai Ninth People's Hospital Affiliated Shanghai Jiao Tong University School of Medicine Shanghai 200011, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Tao
authors.affiliation: Department of General Surgery, Hebei General Hospital Shijiazhuang 050051, Hebei, China.
authors.forename: Fenghua
authors.initials: F
authors.lastname: Zhang
keywords: Esophageal cancer; GSTP1; cancer risk; meta-analysis; polymorphism