title: Distribution of colorectal adenomas: implications for bowel cancer screening.
abstract: OBJECTIVE
  To determine the distribution of colorectal adenomas relative to the splenic flexure in an asymptomatic population undergoing colonoscopy, as an indicator of the number of patients with adenomas who would be missed by screening with flexible sigmoidoscopy.
  
  
  METHODS
  Retrospective survey of medical records.
  
  
  METHODS
  Private endoscopy centres in Melbourne, Victoria.
  
  
  METHODS
  All 1131 asymptomatic individuals who underwent full colonoscopy between 1 January 1995 and 31 December 1997 after referral from a bowel cancer prevention program organised by the endoscopy centres. People referred were aged either 40 years or over with a first-degree relative with bowel cancer, or 50 years or over with marked anxiety about bowel cancer.
  
  
  METHODS
  Presence and distribution of colorectal adenomas.
  
  
  RESULTS
  Polyps were found in 270 individuals (24%) and were confirmed to be adenomas in 138 (12%). These 138 comprised 106 men and 32 women, with mean age 54 years (range, 40-78 years). Most (86%) had a single adenoma. Position of adenomas in relation to the splenic flexure was: distal only in 85 of the 138 people (62%), proximal only in 34 (25%), and both distal and proximal in 19 (14%).
  
  
  CONCLUSIONS
  In 25% of asymptomatic people found to have adenomas by this bowel cancer prevention program, the adenomas were found only in the proximal colon, well beyond the reach of the flexible sigmoidoscope. This distribution of adenomas suggests that screening programs cannot rely solely on flexible sigmoidoscopy.
authors.affiliation: Gastroenterology Unit, Monash Medical Centre, Melbourne, Vic.
authors.forename: F B
authors.initials: FB
authors.lastname: Nicholson
authors.forename: M G
authors.initials: MG
authors.lastname: Korman
authors.forename: A I
authors.initials: AI
authors.lastname: Stern
authors.forename: J
authors.initials: J
authors.lastname: Hansky
mesh_terms: D000236:Adenoma / Q000175:diagnosis / Q000473:pathology*; D000328:Adult; D000368:Aged; D001315:Australia; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012812:Sigmoidoscopy