title: Shortened telomere length is associated with increased risk of cancer: a meta-analysis.
abstract: BACKGROUND
  Telomeres play a key role in the maintenance of chromosome integrity and stability, and telomere shortening is involved in initiation and progression of malignancies. A series of epidemiological studies have examined the association between shortened telomeres and risk of cancers, but the findings remain conflicting.
  
  
  METHODS
  A dataset composed of 11,255 cases and 13,101 controls from 21 publications was included in a meta-analysis to evaluate the association between overall cancer risk or cancer-specific risk and the relative telomere length. Heterogeneity among studies and their publication bias were further assessed by the χ(2)-based Q statistic test and Egger's test, respectively.
  
  
  RESULTS
  The results showed that shorter telomeres were significantly associated with cancer risk (OR = 1.35, 95% CI = 1.14-1.60), compared with longer telomeres. In the stratified analysis by tumor type, the association remained significant in subgroups of bladder cancer (OR = 1.84, 95% CI = 1.38-2.44), lung cancer (OR = 2.39, 95% CI = 1.18-4.88), smoking-related cancers (OR = 2.25, 95% CI = 1.83-2.78), cancers in the digestive system (OR = 1.69, 95% CI = 1.53-1.87) and the urogenital system (OR = 1.73, 95% CI = 1.12-2.67). Furthermore, the results also indicated that the association between the relative telomere length and overall cancer risk was statistically significant in studies of Caucasian subjects, Asian subjects, retrospective designs, hospital-based controls and smaller sample sizes. Funnel plot and Egger's test suggested that there was no publication bias in the current meta-analysis (P = 0.532).
  
  
  CONCLUSIONS
  The results of this meta-analysis suggest that the presence of shortened telomeres may be a marker for susceptibility to human cancer, but single larger, well-design prospective studies are warranted to confirm these findings.
authors.affiliation: Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Ma
authors.forename: Ziyuan
authors.initials: Z
authors.lastname: Zhou
authors.forename: Sheng
authors.initials: S
authors.lastname: Wei
authors.forename: Zhensheng
authors.initials: Z
authors.lastname: Liu
authors.forename: Karen A
authors.initials: KA
authors.lastname: Pooley
authors.forename: Alison M
authors.initials: AM
authors.lastname: Dunning
authors.forename: Ulrika
authors.initials: U
authors.lastname: Svenson
authors.forename: Göran
authors.initials: G
authors.lastname: Roos
authors.forename: H Dean
authors.initials: HD
authors.lastname: Hosgood
authors.forename: Min
authors.initials: M
authors.lastname: Shen
authors.forename: Qingyi
authors.initials: Q
authors.lastname: Wei
mesh_terms: D016001:Confidence Intervals; D020022:Genetic Predisposition to Disease; D006801:Humans; D009369:Neoplasms / Q000235:genetics*; D016017:Odds Ratio; D017594:Publication Bias; D012307:Risk Factors; D016615:Telomere / Q000378:metabolism*