title: The association of telomere length and cancer: a meta-analysis.
abstract: BACKGROUND
  Telomeres shorten with each cell division and are essential for chromosomal stability. Short telomeres in surrogate tissues (e.g., blood cells) are associated with increased cancer risk in several case-control studies, but findings are inconsistent in prospective studies.
  
  
  METHODS
  We systematically reviewed studies published prior to August 30, 2010, on the association between telomere length (TL) in surrogate tissues and cancer. There were 27 reports on 13 cancers and/or incident cancer investigating this association. The majority, 16, were retrospective case--control studies, 11 were prospective studies. Meta-analyses were conducted to determine ORs and 95% CIs for these studies.
  
  
  RESULTS
  Studies on bladder, esophageal, gastric, head and neck, ovarian, renal, and overall incident cancer found associations between short telomeres and these cancers. Non-Hodgkin lymphoma, breast, lung, and colorectal cancer reports were inconsistent. Single studies on endometrial, prostate, and skin cancers were null. In a random-effects meta-analysis, short TL was significantly associated with cancer in retrospective studies (pooled OR for the shortest TL quartile compared with the longest: 2.9, 95% CI: 1.75-4.8, P < 0.0001). The pooled OR for prospective studies was 1.16 (95% CI: 0.87-1.54, P = 0.32). All studies combined yielded a pooled OR of 1.96 (95% CI: 1.37-2.81, P = 0.0001) for the association of short TL and cancer.
  
  
  CONCLUSIONS
  There is suggestive evidence that short surrogate tissue TL is associated with cancer; the strongest evidence exists for bladder, esophageal, gastric, and renal cancers. Additional prospective studies with consistent methodology are needed to confirm this hypothesis.
authors.affiliation: Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Rockville, Maryland 20852, USA.
authors.forename: Ingrid M
authors.initials: IM
authors.lastname: Wentzensen
authors.forename: Lisa
authors.initials: L
authors.lastname: Mirabello
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Pfeiffer
authors.forename: Sharon A
authors.initials: SA
authors.lastname: Savage
mesh_terms: D016022:Case-Control Studies; D043171:Chromosomal Instability; D006801:Humans; D009369:Neoplasms / Q000235:genetics*; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors; D016615:Telomere / Q000235:genetics*