title: The frequency of a positive family history for colorectal cancer: a population-based study in the Netherlands.
abstract: BACKGROUND
  Subjects with a positive family history of colorectal cancer (CRC) have an increased risk of developing CRC themselves. This risk depends on the number of affected relatives and the age at diagnosis.
  
  
  OBJECTIVE
  The aim of this study was to assess the prevalence of a positive family history of CRC, within a random cohort among the dutch population.
  
  
  METHODS
  A total of 5072 subjects aged between 45 and 70 years were invited to fill in an anonymous questionnaire about the occurrence of CRC in their first-degree relatives (FDR).
  
  
  RESULTS
  The questionnaire was returned by 3973 subjects (78.3%). Thirty responders (0.8%) had CRC themselves. Of all unaffected responders, 441 (11.2%) subjects reported a positive family history of CRC. Ninety (2.3%) responders reported having an FDR with CRC diagnosed before the age of 50, or reported two or more FDRs with CRC.
  
  
  CONCLUSIONS
  The prevalence of a positive family history of CRC is substantial. Identification of this high-risk group by obtaining a thorough family history is the first step in targeting preventive measures.
authors.affiliation: The Netherlands Foundation for the Detection of Hereditary Tumours and the Department of Gastroenterology, Leiden University Medical Centre, Leiden, the Netherlands.
authors.forename: A E
authors.initials: AE
authors.lastname: de Jong
authors.forename: H F A
authors.initials: HF
authors.lastname: Vasen
mesh_terms: D000368:Aged; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000453:epidemiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence