title: Cytochrome P450 1A1 exon 7 polymorphism and susceptibility to lung cancer in the Chinese population: an updated meta-analysis and review.
abstract: BACKGROUND
  Although many epidemiologic studies have investigated the cytochrome P450 1A1 (CYP1A1) exon 7 gene polymorphism and its association with lung cancer (LC), definitive conclusions cannot be drawn.
  
  
  OBJECTIVE
  To clarify the effects of CYP1A1 exon 7 polymorphism on the risk of LC, an updated meta-analysis was performed in the Chinese population.
  
  
  METHODS
  Related studies were identified from PubMed, Springer Link, Ovid, the Chinese Wanfang Data Knowledge Service Platform, Chinese National Knowledge Infrastructure (CNKI), and the Chinese Biology Medicine (CBM) databases until October 2014. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the associations.
  
  
  RESULTS
  A total of 25 articles including 3,540 LC cases and 5,284 controls were included in this meta-analysis. Overall, significant association was found between CYP1A1 exon 7 polymorphism and LC risk when all studies in the Chinese population were pooled into this meta-analysis (GG versus AA: OR = 1.71, 95% CI: 1.46-2.01; GG versus AG: OR = 1.41, 95% CI: 1.21-1.64; GG + AG versus AA: OR = 1.37, 95% CI: 1.16-1.62; GG versus AA + AG: OR = 1.52, 95% CI: 1.32-1.76). In subgroup analyses stratified by ethnicity, source of controls, and geographical locations, significantly increased risk was found in Chinese Han people, in population-based studies, in hospital-based studies, in South China, and in North China.
  
  
  CONCLUSIONS
  This meta-analysis provides the evidence that CYP1A1 exon 7 polymorphism may contribute to LC development in the Chinese population, and studies with a larger sample size and wider population spectrum are warranted to verify this finding.
authors.affiliation: Respiratory Department, Beijing Tiantan Hospital affiliated to Capital Medical University, Beijing, People's Republic of China.
authors.forename: Xiu-Ping
authors.initials: XP
authors.lastname: Wei
authors.affiliation: Respiratory Department, Beijing Tiantan Hospital affiliated to Capital Medical University, Beijing, People's Republic of China.
authors.forename: Jie
authors.initials: J
authors.lastname: Hu
keywords: CYP1A1; epidemiology; gene; lung neoplasm