title: Prevention of colorectal cancer by colonoscopic surveillance in individuals with a family history of colorectal cancer: 16 year, prospective, follow-up study.
abstract: OBJECTIVE
  To determine to what extent individuals with various family histories of colorectal cancer (from one to three or more affected first degree relatives) benefit from colonoscopic surveillance.
  
  
  METHODS
  Prospective, observational study of high risk families, followed up over 16 years.
  
  
  METHODS
  Tertiary referral family cancer clinic in London.
  
  
  METHODS
  1678 individuals from families registered with the clinic. Individuals were classified according to the strength of their family history: hereditary non-polyposis colorectal cancer (if they fulfilled the Amsterdam criteria), and one, two, or three affected first degree relatives (moderate risk).
  
  
  METHODS
  Colonoscopy was initially offered at five year intervals or three year intervals if an adenoma was detected.
  
  
  METHODS
  The incidence of adenomas with high risk pathological features or cancer. This was analysed by age, the extent of the family history, and findings on previous colonoscopies. The cohort was flagged for cancer and death. Incidence of colorectal cancer and mortality during over 15,000 person years of follow-up were compared with those expected in the absence of surveillance.
  
  
  RESULTS
  High risk adenomas and cancer were most common in families with hereditary non-polyposis colorectal cancer (on initial colonoscopy 5.7% and 0.9%, respectively). In the families with moderate risk, these findings were particularly uncommon under age 45 (1.1% and 0%) and on follow-up colonoscopy if advanced neoplasia was absent initially (1.7% and 0.1%). The incidence of colorectal cancer was substantially lower-80% in families with moderate risk (P = 0.00004), and 43% in families with hereditary non-polyposis colorectal cancer (P = 0.06)-than the expected incidence in the absence of surveillance when the family history was taken into account.
  
  
  CONCLUSIONS
  Colonoscopic surveillance reduces the risk of colorectal cancer in people with a strong family history. This study confirms that members of families with hereditary non-polyposis colorectal cancer require surveillance with short intervals. Individuals with a lesser family history may not require surveillance under age 45, and if advanced neoplasia is absent on initial colonoscopy, surveillance intervals may be lengthened. This would reduce the demand for colonoscopic surveillance.
authors.affiliation: Family Cancer Group, Cancer Research UK Colorectal Cancer Unit, St Mark's Hospital, Harrow, Middlesex HA1 3UJ.
authors.forename: Isis
authors.initials: I
authors.lastname: Dove-Edwin
authors.forename: Peter
authors.initials: P
authors.lastname: Sasieni
authors.forename: Joanna
authors.initials: J
authors.lastname: Adams
authors.forename: Huw J W
authors.initials: HJ
authors.lastname: Thomas
mesh_terms: D000328:Adult; D000368:Aged; D003113:Colonoscopy / Q000379:methods*; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000401:mortality / Q000517:prevention & control*; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008131:London / Q000453:epidemiology; D008875:Middle Aged; D010375:Pedigree; D011446:Prospective Studies; D012307:Risk Factors