title: Prevalence of advanced adenomas in small and diminutive colon polyps using direct measurement of size.
abstract: OBJECTIVE
  Most studies reporting polyp size use visual estimates. Determining the prevalence of advanced histology based on direct measurement of polyp size may help guide the management of polyps found at optical colonoscopy (OC) and CT colonography (CTC).
  
  
  METHODS
  We designed a large, prospective study to assess the prevalence of advanced adenomas based on direct measurement of polyp size by a certified pathologists' assistant as reported in the pathology report. Patients between 40 and 89 years of age who presented for screening colonoscopy were included in our study. Advanced adenomas were defined as ≥10 mm or ≥25% villous features, high grade dysplasia or cancer. Polyps were divided by size into three groups: diminutive (≤5 mm), small (6-9 mm) and large (≥10 mm). If more than one adenoma was present, the most advanced was used for analysis.
  
  
  RESULTS
  We evaluated 6,905 consecutive patients referred for colonoscopy between January 2005 and December 2006. Of the 4,967 who met the inclusion criteria, the mean age was 58.8 and consisted of 59% women. Overall, 930 (18.7%) had an adenoma; 248 (5%) were advanced adenomas including 8 (0.16%) cancers. Of 89 polyps≥10 mm, 76 (85%) had advanced histology; of 247 polyps 6-9 mm, 67 (27%) were advanced; of 1,025 polyps ≤5 mm, 105 (10%) were advanced. Thus, 172 of 248 (69%) patients with advanced adenomas had small or diminutive adenomas.
  
  
  CONCLUSIONS
  Our data indicate the majority (69%) of advanced adenomas are <10 mm. Even among polyps≤5 mm, there was an appreciable prevalence of advanced adenomas (10%). These findings may help guide the management of sub-centimeter colon polyps found by OC or CTC.
authors.affiliation: Division of Gastroenterology, Scripps Clinic and the Scripps Clinic Research Institute, Torrey Pines, 10666 North Torrey Pines Road, La Jolla, CA 92037, USA. tsai.franklin@scrippshealth.org
authors.forename: Franklin C
authors.initials: FC
authors.lastname: Tsai
authors.forename: Williamson B
authors.initials: WB
authors.lastname: Strum
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003110:Colonic Neoplasms / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000473:pathology; D003111:Colonic Polyps / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000473:pathology; D023881:Colonography, Computed Tomographic; D003113:Colonoscopy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies