title: Likelihood of missed and recurrent adenomas in the proximal versus the distal colon.
abstract: BACKGROUND
  Colonoscopy may be less efficacious in reducing colorectal cancer mortality in the proximal compared with the distal colon. A greater likelihood for missed and recurrent adenomas in the proximal colon may contribute to this phenomenon.
  
  
  OBJECTIVE
  To examine whether a proximal adenoma is associated with the risk and location of missed and recurrent adenomas.
  
  
  METHODS
  Prospective.
  
  
  METHODS
  Polyp Prevention Trial.
  
  
  METHODS
  A total of 1864 patients with an adenoma at baseline underwent a follow-up colonoscopy 4 years later (adenoma recurrence). Of these, 1731 underwent a clearing colonoscopy 1 year after the baseline examination (missed adenoma).
  
  
  METHODS
  Association of baseline adenoma location with the risk and location of adenomas found at colonoscopy performed 1 year and 4 years later.
  
  
  RESULTS
  At the year 1 colonoscopy, 598 patients (34.6%) had an adenoma (missed adenoma). Compared with those with a distal-only adenoma at baseline, patients with a proximal-only adenoma at baseline were more likely to have any missed adenomas (relative risk [RR] 1.28; 95% CI, 1.09-1.49) and a proximal-only missed adenoma (RR 2.05; 95% CI, 1.49-2.80). At the year 4 colonoscopy, 733 patients (39.3%) had adenoma recurrence. Patients with a baseline proximal-only adenoma were more likely to have any adenoma recurrence (RR 1.14; 95% CI, 1.00-1.31) and a proximal-only adenoma recurrence (RR 1.52; 95% CI, 1.15-2.02). Sensitivity analyses involving missed adenomas did not materially affect the risk or location of recurrent adenomas at year 4 colonoscopy.
  
  
  CONCLUSIONS
  Lesions may still be missed on repeated colonoscopies.
  
  
  CONCLUSIONS
  Missed and recurrent adenomas are more likely to be in the proximal colon.
authors.affiliation: Department of Medicine, Howard University College of Medicine, Washington, DC, USA. adeyinka.laiyemo@howard.edu
authors.forename: Adeyinka O
authors.initials: AO
authors.lastname: Laiyemo
authors.forename: Chyke
authors.initials: C
authors.lastname: Doubeni
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Sanderson
authors.forename: Paul F
authors.initials: PF
authors.lastname: Pinsky
authors.forename: Dilhana S
authors.initials: DS
authors.lastname: Badurdeen
authors.forename: V Paul
authors.initials: VP
authors.lastname: Doria-Rose
authors.forename: Pamela M
authors.initials: PM
authors.lastname: Marcus
authors.forename: Robert E
authors.initials: RE
authors.lastname: Schoen
authors.forename: Elaine
authors.initials: E
authors.lastname: Lanza
authors.forename: Arthur
authors.initials: A
authors.lastname: Schatzkin
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Cross
mesh_terms: D000236:Adenoma / Q000175:diagnosis*; D000368:Aged; D044682:Colon, Ascending / Q000473:pathology*; D044683:Colon, Descending / Q000473:pathology*; D012809:Colon, Sigmoid / Q000473:pathology*; D044684:Colon, Transverse / Q000473:pathology*; D003110:Colonic Neoplasms / Q000175:diagnosis*; D003113:Colonoscopy; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis*; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors