title: Efficacy of Vitamin and Antioxidant Supplements in Prevention of Esophageal Cancer: Meta-analysis of Randomized Controlled Trials.
abstract: BACKGROUND
  Observational epidemiological studies have shown that higher intakes of vitamins or antioxidants were inversely associated with the risk of esophageal cancer. However, randomized controlled trials (RCTs) have reported no preventive efficacy of vitamin or antioxidant supplements on esophageal cancer. This meta-analysis aimed to investigate the efficacy of vitamin and antioxidant supplements in the prevention of esophageal cancer as reported by RCTs.
  
  
  METHODS
  We searched PubMed, EMBASE, and the Cochrane Library in May 2013. Two authors independently reviewed and selected eligible articles based on predetermined selection criteria.
  
  
  RESULTS
  Of 171 articles searched from three databases and relevant bibliographies, 10 RCTs were included in the final analyses. In a fixed-effect meta-analysis of 10 trials, there was no efficacy of vitamin and antioxidant supplements in the prevention of esophageal cancer (relative risk [RR], 1.04; 95% confidence interval [CI], 0.86-1.25; I(2)=0.0%). Also, subgroup meta-analyses showed that vitamin and antioxidant supplements had no preventive efficacy on esophageal cancer both in the high risk (RR, 1.04; 95% CI, 0.85-1.28; n=4) and non-high risk (RR, 1.01; 95% CI, 0.65-1.56; n=6) groups for esophageal cancer. Further, subgroup meta-analyses revealed no preventive efficacy on esophageal cancer by type of methodological quality and type of vitamin and antioxidant supplements.
  
  
  CONCLUSIONS
  Unlike observational epidemiological studies, this meta-analysis of RCTs suggests that there is no clinical evidence to support the efficacy of vitamin and antioxidant supplements in the prevention of esophageal cancer.
authors.affiliation: Department of Family Medicine, Hospital, National Cancer Center ; Cancer Information & Education Branch, National Cancer Control Institute, National Cancer Center ; Center for Cancer Prevention and Detection, Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Seung-Kwon
authors.initials: SK
authors.lastname: Myung
authors.affiliation: Department of Family Medicine, Hospital, National Cancer Center ; Center for Cancer Prevention and Detection, Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Hyo Jin
authors.initials: HJ
authors.lastname: Yang
keywords: Antioxidant supplements; Esophageal cancer; Meta-analysis; Randomized controlled trials; Vitamin supplements