title: Decreased colorectal cancer and adenoma risk in patients with microscopic colitis.
abstract: BACKGROUND
  Microscopic colitis is currently considered to harbor no increased risk for colorectal cancer, based on a few small studies with limited long-term follow-up. Our aim was to identify patients with microscopic colitis, and to compare long-term rates of colorectal cancer or adenoma to a control group of patients without microscopic colitis.
  
  
  METHODS
  We reviewed the records of patients diagnosed with microscopic colitis, as identified by a hospital-based pathology database from January 2000 to August 2008. Clinical factors, including history of adenoma or adenocarcinoma, and all colonoscopy findings, were recorded. Age and gender-matched patients without microscopic colitis served as the control in a 1:1 fashion.
  
  
  RESULTS
  A total of 647 patients (153 male: 494 female) were identified with microscopic colitis (MC). Any history of colorectal cancer was detected in 1.92, 1.81, and 4.17% of patients with collagenous colitis (CC), lymphocytic colitis (LC), and controls, respectively (P = 0.095, P = 0.040, P = 0.015 for CC, LC, and all MC, respectively, comparing to controls). Overall, covariate-adjusted risk (odds ratio) of any history of colorectal cancer and colorectal adenoma in MC patients was 0.34 (95% confidence interval [CI] 0.16-0.73, P = 0.006) and 0.52 (95% CI 0.50-0.76, P < 0.0001), respectively. The mean duration of follow-up was 4.63 years, with 147/647 (22.7%) of patients with clinical follow-up >7 years.
  
  
  CONCLUSIONS
  In this case-control study involving a large retrospective cohort, microscopic colitis is negatively associated with the risk for colorectal cancer and adenoma. Further studies are required to determine a temporal relationship between microscopic colitis and the future development of colorectal neoplasia.
authors.affiliation: Division of Gastroenterology, Pritzker School of Medicine, University of Chicago, NorthShore University HealthSystem, 2650 Ridge Avenue, Suite G221, Evanston, IL 60201, USA. eyen@uchicago.edu
authors.forename: Eugene F
authors.initials: EF
authors.lastname: Yen
authors.forename: Bhupesh
authors.initials: B
authors.lastname: Pokhrel
authors.forename: Laura K
authors.initials: LK
authors.lastname: Bianchi
authors.forename: Hemant K
authors.initials: HK
authors.lastname: Roy
authors.forename: Hongyan
authors.initials: H
authors.lastname: Du
authors.forename: Amir
authors.initials: A
authors.lastname: Patel
authors.forename: Curtis R
authors.initials: CR
authors.lastname: Hall
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Witt
mesh_terms: D000236:Adenoma / Q000175:diagnosis / Q000453:epidemiology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D015331:Cohort Studies; D046728:Colitis, Microscopic / Q000150:complications*; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors