title: Colonic adenomas found via colonoscopy: yield and risk factors for high-grade dysplasia.
abstract: OBJECTIVE
  The adenoma-carcinoma sequence is the model for colorectal carcinoma (CRC) developing through high-grade dysplasia (HGD) to CRC. The aim was to assess prevalence and location of adenomas found during colonoscopy and risk factors for HGD.
  
  
  METHODS
  A population-based study using all colonoscopies and polyp specimens registered between 2000 and 2004 in Iceland. Multiple logistic regression analysis was used to assess independent risk factors for HGD.
  
  
  RESULTS
  A total of 3,315 adenomas were removed from 2,385 patients. Only 14.0% were >1 cm in size. HGD was found in 135 (4.1%) of the adenomas and tubulovillous/villous histology in 15.0%. The prevalence of adenomas in the 50- to 69-year age group was 15.5%, and 21.5% in the >or=70-year group. 60.9% of them were located distal to the splenic flexure. Independent risk factors for HGD were in the order of importance: size; multiplicity; tubulovillous/villous histology; location in rectum, and age. The prevalence of HGD in the group with an adenoma size of 0.6-1.0 cm was 4.1% and in the 40- to 69-year age group it was 3.7%.
  
  
  CONCLUSIONS
  The study suggests a potential 15% yield per colonoscopy of adenomas in 50- to 69-year-olds. There is an appreciable risk of HGD in diminutive polyps and in middle age.
authors.affiliation: Speglun ehf, Reykjavík, Iceland. skris@mmedia.is
authors.forename: Sjofn
authors.initials: S
authors.lastname: Kristjansdottir
authors.forename: Jon G
authors.initials: JG
authors.lastname: Jonasson
authors.forename: Nick
authors.initials: N
authors.lastname: Cariglia
authors.forename: Bjarni
authors.initials: B
authors.lastname: Thjodleifsson
mesh_terms: D000236:Adenoma / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D000328:Adult; D000368:Aged; D016009:Chi-Square Distribution; D003111:Colonic Polyps / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D007055:Iceland / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011230:Precancerous Conditions / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery; D015995:Prevalence; D012042:Registries; D012307:Risk Factors