title: Shorter peripheral blood telomeres are a potential biomarker for patients with advanced colorectal adenomas.
abstract: BACKGROUND
  Colorectal cancer (CRC) can be prevented by the early detection and removal of advanced adenomas (AAs) by colonoscopy. Our aim was to evaluate peripheral blood leukocyte (PBL) telomere length as a potential biomarker for the presence of AAs.
  
  
  METHODS
  PBL telomere length was measured in patients with AAs (n=35), in a control group of similarly aged patients who had a normal colonoscopy (n=145) and in a separate population group with no history of cancer, again similarly aged (n=495). Telomere measurements were performed using a quantitative PCR assay and reported as ratios of telomere and single copy gene measurements.
  
  
  RESULTS
  Telomere lengths tended to be lower in patients with AAs than in patients in the normal colonoscopy group (p<0.001) as well as those in the population group (p=0.011). A telomere/single copy gene ratio of 0.5 was found to have an estimated 94% sensitivity and a 56% specificity for AAs; a combination of sensitivity and specificity for which a value of >0.5 would reduce the odds of a patient having AAs by a factor of 0.11 (the negative likelihood ratio). Thirty three percent of individuals in the population group tested above this cutoff and could be considered at low risk for AAs.
  
  
  CONCLUSIONS
  PBL telomeres are shortened in patients with colorectal neoplasia, suggesting that PBL telomere length could be a promising non-invasive blood biomarker to pre-screen for risk of AAs prior to colonoscopy.
authors.affiliation: Medical Genetics, Mayo Clinic, Jacksonville, Florida, USA.
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Riegert-Johnson
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Boardman
authors.forename: Julia E
authors.initials: JE
authors.lastname: Crook
authors.forename: Colleen S
authors.initials: CS
authors.lastname: Thomas
authors.forename: Ruth A
authors.initials: RA
authors.lastname: Johnson
authors.forename: Maegan E
authors.initials: ME
authors.lastname: Roberts
mesh_terms: D000236:Adenoma / Q000097:blood / Q000235:genetics* / Q000473:pathology; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood / Q000235:genetics*; D003113:Colonoscopy / Q000379:methods; D015179:Colorectal Neoplasms / Q000097:blood / Q000235:genetics* / Q000473:pathology; D005260:Female; D006801:Humans; D007962:Leukocytes / Q000648:ultrastructure; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016615:Telomere / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D014408:Biomarkers, Tumor