title: Family history and the natural history of colorectal cancer: systematic review.
abstract: OBJECTIVE
  Family history of colorectal cancer (CRC) is a known risk factor for CRC and encompasses both genetic and shared environmental risks.
  
  
  METHODS
  We conducted a systematic review to estimate the impact of family history on the natural history of CRC and adherence to screening.
  
  
  RESULTS
  We found high heterogeneity in family-history definitions, the most common definition being one or more first-degree relatives. The prevalence of family history may be lower than the commonly cited 10%, and confirms evidence for increasing levels of risk associated with increasing family-history burden. There is evidence for higher prevalence of adenomas and of multiple adenomas in people with family history of CRC but no evidence for differential adenoma location or adenoma progression by family history. Limited data regarding the natural history of CRC by family history suggest a differential age or stage at cancer diagnosis and mixed evidence with respect to tumor location. Adherence to recommended colonoscopy screening was higher in people with a family history of CRC.
  
  
  CONCLUSIONS
  Stratification based on polygenic and/or multifactorial risk assessment may mature to the point of displacing family history-based approaches, but for the foreseeable future, family history may remain a valuable clinical tool for identifying individuals at increased risk for CRC.
authors.affiliation: Group Health Research Institute, Seattle, Washington, USA.
authors.forename: Nora B
authors.identifier: http://orcid.org/0000-0002-3459-7787
authors.initials: NB
authors.lastname: Henrikson
authors.affiliation: Kaiser Permanente Center for Health Research, Portland, Oregon, USA.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Webber
authors.affiliation: Kaiser Permanente Center for Health Research, Portland, Oregon, USA.
authors.forename: Katrina A
authors.initials: KA
authors.lastname: Goddard
authors.affiliation: Group Health Research Institute, Seattle, Washington, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Scrol
authors.affiliation: Kaiser Permanente Center for Health Research, Portland, Oregon, USA.
authors.forename: Margaret
authors.identifier: http://orcid.org/0000-0002-6231-9653
authors.initials: M
authors.lastname: Piper
authors.affiliation: Geisinger Health System, Genomic Medicine Institute, Danville, Pennsylvania, USA.
authors.forename: Marc S
authors.identifier: http://orcid.org/0000-0001-6165-8701
authors.initials: MS
authors.lastname: Williams
authors.affiliation: Virginia Tech, Blacksburg, Virginia, USA.
authors.forename: Doris T
authors.identifier: http://orcid.org/0000-0002-5688-5640
authors.initials: DT
authors.lastname: Zallen
authors.affiliation: The Colorado Trust, Denver, Colorado, USA.
authors.forename: Ned
authors.identifier: http://orcid.org/0000-0002-2653-6001
authors.initials: N
authors.lastname: Calonge
authors.affiliation: University of California, San Diego, San Diego, California, USA.
authors.forename: Theodore G
authors.identifier: http://orcid.org/0000-0002-3920-3708
authors.initials: TG
authors.lastname: Ganiats
authors.affiliation: Emory University, Atlanta, Georgia, USA.
authors.forename: A Cecile J W
authors.identifier: http://orcid.org/0000-0002-6153-4976
authors.initials: AC
authors.lastname: Janssens
authors.affiliation: Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
authors.forename: Ann
authors.initials: A
authors.lastname: Zauber
authors.affiliation: Department of Health, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Iris
authors.initials: I
authors.lastname: Lansdorp-Vogelaar
authors.affiliation: Department of Health, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Marjolein
authors.initials: M
authors.lastname: van Ballegooijen
authors.affiliation: Kaiser Permanente Center for Health Research, Portland, Oregon, USA.
authors.forename: Evelyn P
authors.initials: EP
authors.lastname: Whitlock
mesh_terms: D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology*; D055088:Early Detection of Cancer; D005192:Family Health; D020022:Genetic Predisposition to Disease; D006801:Humans; D015995:Prevalence; D012307:Risk Factors