title: Association between cigarette smoking and RASSF1A gene promoter hypermethylation in lung cancer patients: a meta- analysis.
abstract: OBJECTIVE
  Epidemiological studies have shown that molecular mechanisms underlying the development of lung cancers differ between smokers and unsmokers. Aberrant promoter methylation in some tumor suppressor genes is frequent in lung tumors from smokers but rare in those from non-smokers. Recently, many studies have investigated the association between cigarette smoking and RASSF1A gene promoter hypermethylation in lung cancer patients, but a unanimous conclusion could not be reached. We therefore performed this meta-analysis to derive a more precise estimation of any association.
  
  
  METHODS
  An electronic search of PubMed and Chinese Biomedicine databases was conducted to select studies. A total of 19 case-control studies were chosen, and odds ratios (ORs) with confidence intervals (CIs) were used to assess the strength of associations.
  
  
  RESULTS
  The case-control studies covered 2, 287 lung cancer patients: 63.4%(1449) of the patients were smokers, 36.6% (838) were unsmokers. The overall results suggested that smokers with lung cancer had a 1.297-fold (95% CI: 1.066~1.580, p=0.010, p=0.087) higher risk for RASSF1A gene hypermethylation than the non-smokers. In the stratified analysis, an increased risk of RASSF1A gene hypermethylation in smokers than in non-smokers was found in Asian (OR=1.481, 95%CI: 1.179~1.861, p=0.001, p=0.186).
  
  
  CONCLUSIONS
  This meta-analysis supports the idea that RASSF1A gene hypermethylation is associated with cigarette smoking-induced lung cancer.
authors.affiliation: Laboratory of Molecular Genetics of Aging and Tumor, Medical Faculty, Kunming University of Science and Technology, Kunming, Yunnan, China E-mail : twr@sina.com.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Wu
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.forename: Yang
authors.initials: Y
authors.lastname: Shao
authors.forename: Xiao-Long
authors.initials: XL
authors.lastname: Zhou
authors.forename: Wen-Ru
authors.initials: WR
authors.lastname: Tang
mesh_terms: D016022:Case-Control Studies; D019175:DNA Methylation; D006801:Humans; D008175:Lung Neoplasms / Q000209:etiology*; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: C411762:RASSF1 protein, human; D025521:Tumor Suppressor Proteins