title: Clinicopathologic features of patients with non-small cell lung cancer harboring the EML4-ALK fusion gene: a meta-analysis.
abstract: BACKGROUND
  The frequencies of EML4-ALK fusion gene in non-small cell lung cancer (NSCLC) with different clinicopathologic features described by previous studies are inconsistent. The key demographic and pathologic features associated with EML4-ALK fusion gene have not been definitively established. This meta-analysis was conducted to compare the frequency of the EML4-ALK fusion gene in patients with different clinicopathologic features and to identify an enriched population of patients with NSCLC harboring EML4-ALK fusion gene.
  
  
  METHODS
  The Pubmed and Embase databases for all studies on EML4-ALK fusion gene in NSCLC patients were searched up to July 2014. A criteria list and exclusion criteria were established to screen the studies. The frequency of the EML4-ALK fusion gene and the clinicopathologic features, including smoking status, pathologic type, gender, and EGFR status were abstracted.
  
  
  RESULTS
  Seventeen articles consisting of 4511 NSCLC cases were included in this meta-analysis. A significant lower EML4-ALK fusion gene positive rate was associated with smokers (pooled OR = 0.40, 95% CI = 0.30-0.54, P<0.00001). A significantly higher EML4-ALK fusion gene positivity rate was associated with adenocarcinomas (pooled OR = 2.53, 95% CI = 1.66-3.86, P<0.0001) and female (pooled OR = 0.61, 95% CI = 0.41-0.90, P = 0.01). We found that a significantly lower EML4-ALK fusion gene positivity rate was associated with EGFR mutation (pooled OR = 0.07, 95% CI = 0.03-0.19, P<0.00001). No publication bias was observed in any meta-analysis (all P value of Egger's test >0.05); however, because of the small sample size, no results were in the meta-analysis regarding EGFR gene status.
  
  
  CONCLUSIONS
  This meta-analysis revealed that the EML4-ALK fusion gene is highly correlated with a never/light smoking history, female and the pathologic type of adenocarcinoma, and is largely mutually exclusive of EGFR.
authors.affiliation: Department of Pathology, Shenyang Medical College, Shenyang, Liaoning, People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Thoracic Department, General Hospital of Shenyang Military Area Command, Shenyang, Liaoning, People's Republic of China.
authors.forename: Shumin
authors.initials: S
authors.lastname: Wang
authors.affiliation: Thoracic Department, General Hospital of Shenyang Military Area Command, Shenyang, Liaoning, People's Republic of China.
authors.forename: Shiguang
authors.initials: S
authors.lastname: Xu
authors.affiliation: Thoracic Department, General Hospital of Shenyang Military Area Command, Shenyang, Liaoning, People's Republic of China.
authors.forename: Jiaqi
authors.initials: J
authors.lastname: Qu
authors.affiliation: Thoracic Department, General Hospital of Shenyang Military Area Command, Shenyang, Liaoning, People's Republic of China.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics* / Q000473:pathology*; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology*; D015514:Oncogene Proteins, Fusion / Q000235:genetics*
chemical_list: C522504:EML4-ALK fusion protein, human; D015514:Oncogene Proteins, Fusion