title: Surveillance colonoscopy in individuals at risk for hereditary nonpolyposis colorectal cancer: an evidence-based review.
abstract: OBJECTIVE
  Surveillance colonoscopy plays an important role in the management of asymptomatic patients known to carry and suspected of carrying hereditary nonpolyposis colorectal cancer gene mutations. Although the shortest interval between surveillance examinations may seem to offer the most benefit to patients, excessive use of this procedure may have unwanted consequences. This study was designed to evaluate the evidence and make recommendations regarding the optimal frequency of surveillance colonoscopy and the age at which to initiate surveillance based on the best available evidence.
  
  
  METHODS
  MEDLINE was searched for all articles assessing surveillance colonoscopy from 1966 to 2004 by using the MESH terms "hereditary nonpolyposis colorectal cancer" and "screening." The evidence was systematically reviewed and a critical appraisal of the evidence was performed.
  
  
  RESULTS
  There are no randomized, controlled, clinical trials examining the frequency of surveillance colonoscopy in hereditary nonpolyposis colorectal cancer. Three cohort studies were identified for review. There is one cohort study of good quality that provides evidence that surveillance colonoscopy every three years in patients with hereditary nonpolyposis colorectal cancer reduces the risk of developing colorectal cancer and the risk of death. The two remaining cohort studies provide poor evidence on which to make a recommendation.
  
  
  CONCLUSIONS
  The best available evidence supports surveillance with complete colonoscopy to the cecum every three years in patients with hereditary nonpolyposis colorectal cancer (B recommendation). There is no evidence to support or refute more frequent screening. Further research is required to examine the potential harms and benefits of more frequent screening. However, given the potential for rapid progression from adenoma to carcinoma and missing lesions at colonoscopy, there is consensus that screening more frequently than every three years is required.
authors.affiliation: IBD Research Unit, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Johnson
authors.forename: Steven
authors.initials: S
authors.lastname: Gallinger
authors.forename: Robin S
authors.initials: RS
authors.lastname: McLeod
mesh_terms: D003113:Colonoscopy; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics; D014943:Global Health; D006801:Humans; D008403:Mass Screening / Q000379:methods*; D017410:Practice Guidelines as Topic; D015995:Prevalence; D012307:Risk Factors