title: Decreasing risk of colorectal cancer in patients with inflammatory bowel disease over 30 years.
abstract: OBJECTIVE
  The risk for colorectal cancer (CRC) in patients with inflammatory bowel disease (IBD) could have changed over time, with changes in treatment options. We studied CRC risk in a nationwide cohort of 47,374 Danish patients with IBD over a 30-year period.
  
  
  METHODS
  We determined relative risk (RR) values using Poisson regression-derived incidence rate ratios of CRC from 1 year after IBD diagnosis, adjusted for age, sex, and calendar time. We compared incidence of CRC among patients with IBD vs individuals without IBD.
  
  
  RESULTS
  During 178 million person-years of follow-up evaluation, 268 patients with ulcerative colitis (UC) and 70 patients with Crohn's disease (CD) developed CRC. The overall risk of CRC among patients with UC was comparable with that of the general population (RR, 1.07; 95% confidence interval [CI], 0.95-1.21). However, patients diagnosed with UC in childhood or as adolescents, those with long duration of disease, and those with concomitant primary sclerosing cholangitis were at increased risk. For patients with UC, the overall RR for CRC decreased from 1.34 (95% CI, 1.13-1.58) in 1979-1988 to 0.57 (95% CI, 0.41-0.80) in 1999-2008. Among patients with CD, the overall RR for CRC was 0.85 (95% CI, 0.67-1.07), which did not change over time.
  
  
  CONCLUSIONS
  A diagnosis of UC or CD no longer seems to increase patients' risk of CRC, although subgroups of patients with UC remain at increased risk. The decreasing risk for CRC from 1979 to 2008 might result from improved therapies for patients with IBD.
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark. tjs@ssi.dk
authors.forename: Tine
authors.initials: T
authors.lastname: Jess
authors.forename: Jacob
authors.initials: J
authors.lastname: Simonsen
authors.forename: Kristian Tore
authors.initials: KT
authors.lastname: Jørgensen
authors.forename: Bo Vestergaard
authors.initials: BV
authors.lastname: Pedersen
authors.forename: Nete Munk
authors.initials: NM
authors.lastname: Nielsen
authors.forename: Morten
authors.initials: M
authors.lastname: Frisch
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D015209:Cholangitis, Sclerosing / Q000150:complications; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000209:etiology*; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007223:Infant; D015212:Inflammatory Bowel Diseases / Q000150:complications*; D008297:Male; D008875:Middle Aged; D016012:Poisson Distribution; D012042:Registries; D012044:Regression Analysis; D012306:Risk; D055815:Young Adult