title: Colorectal cancer in patients under close colonoscopic surveillance.
abstract: OBJECTIVE
  Colonoscopic polypectomy is considered effective for preventing colorectal cancer (CRC), but the incidence of cancer in patients under colonoscopic surveillance has rarely been investigated. We determined the incidence of CRC in patients under colonoscopic surveillance and examined the circumstances and risk factors for CRC and adenoma with high-grade dysplasia.
  
  
  METHODS
  Patients were drawn from 3 adenoma chemoprevention trials. All underwent baseline colonoscopy with removal of at least one adenoma and were deemed free of remaining lesions. We identified patients subsequently diagnosed with invasive cancer or adenoma with high-grade dysplasia. The timing, location, and outcome of all cases of cancer and high-grade dysplasia identified are described and risks associated with their development explored.
  
  
  RESULTS
  CRC was diagnosed in 19 of the 2915 patients over a mean follow-up of 3.7 years (incidence, 1.74 cancers/1000 person-years). The cancers were located in all regions of the colon; 10 were at or proximal to the hepatic flexure. Although most of the cancers (84%) were of early stage, 2 participants died of CRC. Seven patients were diagnosed with adenoma with high-grade dysplasia during follow-up. Older patients and those with a history of more adenomas were at higher risk of being diagnosed with invasive cancer or adenoma with high-grade dysplasia.
  
  
  CONCLUSIONS
  CRC is diagnosed in a clinically important proportion of patients following complete colonoscopy and polypectomy. More precise and representative estimates of CRC incidence and death among patients undergoing surveillance examinations are needed.
authors: Section of Gastroenterology, VA Medical Center, White River Junction, Vermont 05009, USA. douglas.robertson@med.va.gov
authors: Douglas J
authors: DJ
authors: Robertson
authors: E Robert
authors: ER
authors: Greenberg
authors: Michael
authors: M
authors: Beach
authors: Robert S
authors: RS
authors: Sandler
authors: Dennis
authors: D
authors: Ahnen
authors: Robert W
authors: RW
authors: Haile
authors: Carol A
authors: CA
authors: Burke
authors: Dale C
authors: DC
authors: Snover
authors: Robert S
authors: RS
authors: Bresalier
authors: Gail
authors: G
authors: McKeown-Eyssen
authors: Jack S
authors: JS
authors: Mandel
authors: John H
authors: JH
authors: Bond
authors: Rosalind U
authors: RU
authors: Van Stolk
authors: Robert W
authors: RW
authors: Summers
authors: Richard
authors: R
authors: Rothstein
authors: Timothy R
authors: TR
authors: Church
authors: Bernard F
authors: BF
authors: Cole
authors: Tim
authors: T
authors: Byers
authors: Leila
authors: L
authors: Mott
authors: John A
authors: JA
authors: Baron
mesh_terms: D000236:Adenoma / Q000175:diagnosis* / Q000453:epidemiology* / Q000517:prevention & control; D000368:Aged; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000453:epidemiology* / Q000517:prevention & control; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012307:Risk Factors