title: The association of telomere length with colorectal cancer differs by the age of cancer onset.
abstract: OBJECTIVE
  Telomeres are nucleoprotein structures that cap the end of chromosomes and shorten with sequential cell divisions in normal aging. Short telomeres are also implicated in the incidence of many cancers, but the evidence is not conclusive for colorectal cancer (CRC). Therefore, the aim of this study was to assess the association of CRC and telomere length.
  
  
  METHODS
  In this case-control study, we measured relative telomere length from peripheral blood leukocytes (PBLs) DNA with quantitative PCR in 598 CRC patients and 2,212 healthy controls.
  
  
  RESULTS
  Multivariate analysis indicated that telomere length was associated with risk for CRC, and this association varied in an age-related manner; younger individuals (≤50 years of age) with longer telomeres (80-99 percentiles) had a 2-6 times higher risk of CRC, while older individuals (>50 years of age) with shortened telomeres (1-10 percentiles) had 2-12 times the risk for CRC. The risk for CRC varies with extremes in telomere length in an age-associated manner.
  
  
  CONCLUSIONS
  Younger individuals with longer telomeres or older individuals with shorter telomeres are at higher risk for CRC. These findings indicate that the association of PBL telomere length varies according to the age of cancer onset and that CRC is likely associated with at minimum two different mechanisms of telomere dynamics.
authors.affiliation: Department of Gastroenterology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Boardman
authors.affiliation: Department of Population Health Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Kristin
authors.initials: K
authors.lastname: Litzelman
authors.affiliation: National Radiation Emergency Medical Center, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
authors.forename: Songwon
authors.initials: S
authors.lastname: Seo
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Ruth A
authors.initials: RA
authors.lastname: Johnson
authors.affiliation: Mayo Clinic Cancer Center, Rochester, Minnesota, USA.
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Vanderboom
authors.affiliation: University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Grace W
authors.initials: GW
authors.lastname: Kimmel
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Cunningham
authors.affiliation: Department of Biostatistics and Medical Informatics, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Gangnon
authors.affiliation: Department of Population Health Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Corinne D
authors.initials: CD
authors.lastname: Engelman
authors.affiliation: Department of Gastroenterology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Riegert-Johnson
authors.affiliation: Public Health Sciences Division, Cancer Prevention Program, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.
authors.forename: John
authors.initials: J
authors.lastname: Potter
authors.affiliation: Department of Oncology, Stanford School of Medicine, The Stanford Cancer Institute, Stanford, California, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Haile
authors.affiliation: Queensland Institute of Medical Research, Clive Berghofer Cancer Research Centre, Brisbane, Queensland, Australia.
authors.forename: Daniel
authors.initials: D
authors.lastname: Buchanan
authors.affiliation: Melbourne School of Population Health, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Jenkins
authors.affiliation: Department of Health Sciences Research, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: David N
authors.initials: DN
authors.lastname: Rider
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Stephen N
authors.initials: SN
authors.lastname: Thibodeau
authors.affiliation: Department of Health Sciences Research, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Gloria M
authors.initials: GM
authors.lastname: Petersen
authors.affiliation: Department of Population Health Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Halcyon G
authors.initials: HG
authors.lastname: Skinner