title: Prevalence of adenomas among young individuals at average risk for colorectal cancer.
abstract: OBJECTIVE
  We evaluated the prevalence and characteristics of adenomas in a young population not genetically predisposed for the development of colorectal cancer (CRC).
  
  
  METHODS
  The databases of the Dutch Hereditary Colorectal Cancer Registry were used. The study population included patients (n = 444) who had regular endoscopy until mutation analysis revealed they did not carry the (Adenomatous Polyposis Coli (APC)/Mismatch Repair) gene defect identified in their family.
  
  
  RESULTS
  At first colonoscopy (n = 342; 50% males, mean age 37 yr) a total of 19 adenomas (10 males, mean age 50 yr, range 24-91 yr) and two CRCs (2 males, age 49 and 72 yr) were identified, and at first sigmoidoscopy (n = 102; 53% males, mean age 29 yr) three adenomas (2 males, age 8, 40, and 41 yr) were found. A second colonoscopy was performed in 14 patients with, and in 162 patients without an adenoma. Three of 14 patients (21%) developed a new adenoma (all >50 yr) and 8 of 162 (5%) patients developed their first adenoma during follow-up. In the colonoscopy group, the cumulative proportion of patients free of adenomas at age 50 yr was 86%. Of all adenomas diagnosed during colonoscopy (n = 49), 65% were located distal from the flexura lienalis. Of the adenomas detected during all endoscopies (n = 53), 9.8% were > or =7 mm, 7.5% showed high-grade dysplasia, and 7.5% showed tubulovillous features.
  
  
  CONCLUSIONS
  On the basis of our findings during colonoscopy we conclude that the risk of developing adenomas/CRC in young individuals without genetic risk factors is low. Adenoma surveillance programs should focus on young individuals with a positive family (or personal) history for adenomas/CRC, or on individuals >50 yr.
authors.affiliation: The Netherlands Foundation for the Detection of Hereditary Tumours, Leiden University medical Center, Poortgebouw Zuid, 2333 AA Leiden, The Netherlands.
authors.forename: Andrea E
authors.initials: AE
authors.lastname: de Jong
authors.forename: Hans
authors.initials: H
authors.lastname: Morreau
authors.forename: Fokko M
authors.initials: FM
authors.lastname: Nagengast
authors.forename: Elisabeth M H
authors.initials: EM
authors.lastname: Mathus-Vliegen
authors.forename: Jan H
authors.initials: JH
authors.lastname: Kleibeuker
authors.forename: Gerrit
authors.initials: G
authors.lastname: Griffioen
authors.forename: Annemieke
authors.initials: A
authors.lastname: Cats
authors.forename: Hans F A
authors.initials: HF
authors.lastname: Vasen
mesh_terms: D000236:Adenoma / Q000453:epidemiology* / Q000209:etiology / Q000473:pathology; D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002648:Child; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000209:etiology / Q000473:pathology; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D018570:Risk Assessment; D017678:Sex Distribution