title: Five-year risk of colorectal neoplasia after negative screening colonoscopy.
abstract: BACKGROUND
  The appropriate interval for endoscopic rescreening after a negative colonoscopic examination is uncertain.
  
  
  METHODS
  We identified persons with no adenomas on baseline screening colonoscopy who returned at 5 years for follow-up colonoscopy. Findings were categorized according to the most advanced lesion present: no polyp, a hyperplastic polyp, a tubular adenoma less than 1 cm in diameter, an advanced adenoma (a tubular adenoma > or = 1 cm in diameter or a polyp with villous histologic features or high-grade dysplasia), or a cancer.
  
  
  RESULTS
  Baseline screening colonoscopy had identified 2436 persons with no adenomas; 1256 of them (51.6%) were rescreened a mean (+/-SD) of 5.34+/-1.34 years later. The mean age of this group at baseline was 56.7 years; 56.7% of its members were men. No cancers were found on rescreening (95% confidence interval [CI] for the detection rate, 0 to 0.24%). One or more adenomas were found in 201 persons (16.0%). A total of 19 advanced adenomas, of which 10 (52.6%) were distal to the splenic flexure, were found in 16 persons (1.3%). The risk of an advanced adenoma did not differ significantly between persons with no polyps at baseline and those with hyperplastic polyps at baseline (1.1% [12 of 1057] and 2.0% [4 of 199], respectively; P=0.30). Men were more likely than women to have any adenoma (tubular less than 1 cm in diameter or advanced) (relative risk, 1.88; 95% CI, 1.42 to 2.51) and to have an advanced adenoma (relative risk, 3.31; 95% CI, 1.02 to 10.8).
  
  
  CONCLUSIONS
  Among persons with no colorectal neoplasia on initial screening colonoscopy, the 5-year risk of colorectal cancer is extremely low. The risk of advanced adenoma is also low, although it is higher among men than among women. Our findings support a rescreening interval of 5 years or longer after a normal colonoscopic examination.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Medicine, Indiana University School of Medicine, Indianapolis, USA.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Imperiale
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Glowinski
authors.forename: Ching
authors.initials: C
authors.lastname: Lin-Cooper
authors.forename: Gregory N
authors.initials: GN
authors.lastname: Larkin
authors.forename: James D
authors.initials: JD
authors.lastname: Rogge
authors.forename: David F
authors.initials: DF
authors.lastname: Ransohoff
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000453:epidemiology*; D000236:Adenoma / Q000175:diagnosis / Q000453:epidemiology*; D003111:Colonic Polyps / Q000175:diagnosis / Q000453:epidemiology*; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012306:Risk; D012680:Sensitivity and Specificity; D013997:Time Factors