title: A direct comparison of the prevalence of advanced adenoma and cancer between surveillance and screening colonoscopies.
abstract: OBJECTIVE
  Surveillance colonoscopy is recommended after polypectomy of adenoma and surgery for colorectal cancer. The purpose of this study was to assess the frequency of advanced adenoma and cancer in colonoscopies performed for surveillance compared to screening colonoscopies.
  
  
  METHODS
  Analysis of relative frequencies of findings in colonoscopies performed for post-adenoma surveillance (post-ad), post-cancer surveillance (post-crc), screening, and follow-up of a positive fecal occult blood test (FOBT). Logistic regression was used to identify the risk for advanced adenoma (adenoma ≥10 mm, containing high-grade dysplasia, or villous histology) and cancer.
  
  
  RESULTS
  324,912 colonoscopies were included in the analysis: 81,877 post-ad, 26,896 post-crc, 178,305 screening, 37,834 positive FOBT. Advanced adenoma (cancer) was diagnosed in 8.0% (0.4%) of post-ad, 5.0% (1.0%) of post-crc, 7.4% (1.1%) of screening, and 11.7% (3.6%) of positive FOBT colonoscopies. Compared to screening, the odds ratios for finding advanced adenoma were 0.93 (95% CI 0.88-0.98) for post-ad, 0.96 (0.86-1.08) for post-crc, and 1.18 (1.09-1.28) for positive FOBT colonoscopies. The odds ratios for the diagnosis of cancer were 0.29 (0.24-0.36) for post-ad, 0.81 (0.61-1.07) for post-crc, and 2.77 (2.43-3.17) for positive FOBT.
  
  
  CONCLUSIONS
  Colonoscopy for post-ad surveillance but not colonoscopy for post-crc surveillance is associated with a lower risk of diagnosis of advanced adenoma and cancer.
authors: Institute of Medical Informatics, Biometry, and Epidemiology, Munich, Germany.
authors: Alexander
authors: A
authors: Crispin
authors: Ulrich
authors: U
authors: Mansmann
authors: Axel
authors: A
authors: Munte
authors: Mark
authors: M
authors: Op den Winkel
authors: Burkhard
authors: B
authors: Göke
authors: Frank Thomas
authors: FT
authors: Kolligs
mesh_terms: D000236:Adenoma / Q000175:diagnosis / Q000453:epidemiology*; D000368:Aged; D002277:Carcinoma / Q000175:diagnosis / Q000453:epidemiology*; D003113:Colonoscopy / Q000706:statistics & numerical data*; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000453:epidemiology*; D011159:Population Surveillance; D015995:Prevalence