title: Risk of cancer in patients with inflammatory bowel diseases: a nationwide population-based cohort study with 30 years of follow-up evaluation.
abstract: OBJECTIVE
  Data regarding the risk of gastrointestinal and extraintestinal cancers in Crohn's disease (CD) and ulcerative colitis (UC) are needed to understand the clinical course of inflammatory bowel diseases (IBDs) and their treatments.
  
  
  METHODS
  We performed a nationwide historical cohort study using Danish health care databases. We identified patients with a diagnosis of CD or UC, recorded from 1978 through 2010, and followed them up until the first occurrence of cancer, death, or emigration. We used standardized incidence ratios (SIRs) to compare cancer incidence in CD and UC patients with that expected in the general population.
  
  
  RESULTS
  Excluding cancers diagnosed within 1 year of IBD diagnosis, 772 cases of invasive cancer occurred among 13,756 patients with CD (SIR, 1.3; 95% confidence interval [CI], 1.2-1.4) and 2331 occurred among 35,152 patients with UC (SIR, 1.1; 95% CI, 1.0-1.1). CD was associated weakly with gastrointestinal cancers (SIR, 1.2; 95% CI, 1.0-1.4) and extraintestinal cancers (SIR, 1.3; 95% CI, 1.2-1.4), with the strongest associations for hematologic malignancies (SIR, 1.9; 95% CI, 1.5-2.3), smoking-related cancers (SIR, 1.5; 95% CI, 1.3-1.8), and melanoma (SIR, 1.4; 95% CI, 1.0-1.9). Associations between UC and gastrointestinal and extraintestinal cancers were weaker (SIR, 1.1; 95% CI, 1.0-1.2; and SIR, 1.1; 95% CI, 1.0-1.1, respectively). The relative risk of extraintestinal cancers among patients with IBD was relatively stable over time, although the risk of gastrointestinal cancers decreased.
  
  
  CONCLUSIONS
  Patients with IBD, particularly CD, are at increased risk for gastrointestinal and extraintestinal malignancies. The relative risk of gastrointestinal malignancy has decreased since 1978, without a concomitant increase in the risk of nongastrointestinal malignancy.
authors.affiliation: Department of Pediatrics, Division of Pediatric Gastroenterology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Electronic address: michael_kappelman@med.unc.edu.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Kappelman
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Dora K
authors.initials: DK
authors.lastname: Farkas
authors.affiliation: Department of Internal Medicine, Division of Gastroenterology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Millie D
authors.initials: MD
authors.lastname: Long
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Rune
authors.initials: R
authors.lastname: Erichsen
authors.affiliation: Department of Internal Medicine, Division of Gastroenterology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Sandler
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Henrik T
authors.initials: HT
authors.lastname: Sørensen
authors.affiliation: Department of Internal Medicine, Division of Gastroenterology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: John A
authors.initials: JA
authors.lastname: Baron
mesh_terms: D015331:Cohort Studies; D003093:Colitis, Ulcerative / Q000453:epidemiology*; D015179:Colorectal Neoplasms / Q000453:epidemiology; D003424:Crohn Disease / Q000453:epidemiology; D003718:Denmark / Q000453:epidemiology; D005770:Gastrointestinal Neoplasms / Q000453:epidemiology; D019337:Hematologic Neoplasms / Q000453:epidemiology; D006801:Humans; D015212:Inflammatory Bowel Diseases; D009369:Neoplasms / Q000453:epidemiology*; D012042:Registries
keywords: CD; CI; Colorectal Cancer; Crohn’s Disease; Crohn’s disease; DCR; DNPR; Danish Cancer Registry; Danish National Patient Register; Epidemiology; GI Tumor; IBD; ICD; International Classification of Diseases; NMSC; SIR; UC; Ulcerative Colitis; confidence interval; inflammatory bowel disease; nonmelanoma skin cancer; standardized incidence ratio; ulcerative colitis