title: Risk of cancer in patients with inflammatory bowel disease and venous thromboembolism: a nationwide cohort study.
abstract: BACKGROUND
  Venous thromboembolism (VTE) may be a harbinger of cancer. Inflammatory bowel disease (IBD) is known to increase the risk of VTE, but it is unclear whether VTE in IBD patients is also a marker for occult cancer. We assessed the risk of cancer after VTE in IBD patients.
  
  
  METHODS
  We conducted a population-based cohort study by linking Danish medical registries during 1978-2008. We calculated standardized incidence ratios (SIRs) by comparing observed cancer incidence after VTE in IBD patients with that expected based on national cancer incidence in the Danish population.
  
  
  RESULTS
  A total of 895 IBD patients with VTE were followed for a total of 5290 person-years. During the first year of follow-up, 28 (3.1%) patients were diagnosed with cancer, corresponding to an SIR of 3.2 (95% confidence interval [CI]: 2.2, 4.7). Patients with ulcerative colitis or Crohn's disease had similar relative risks (SIR = 3.1 [95% CI: 1.9, 4.9] and SIR = 3.5 [95% CI: 1.7, 6.3], respectively). In IBD patients <55 years the SIR was 5.7 (95% CI: 2.3, 11.8) and in patients ≥55 years the SIR was 2.8 (95% CI: 1.8, 4.3). During the second and subsequent years of follow-up 61 cancers were diagnosed (SIR = 1.2 [95% CI: 0.92, 1.6]).
  
  
  CONCLUSIONS
  In patients with IBD a VTE event is not only a consequence of their disease, but might also be a marker of occult cancer. We suggest that IBD patients with VTE should follow the same diagnostic work-up guidelines as non-IBD VTE patients.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Denmark. vrelits@gmail.com
authors.forename: Gitte Vrelits
authors.initials: GV
authors.lastname: Sørensen
authors.forename: Rune
authors.initials: R
authors.lastname: Erichsen
authors.forename: Claus
authors.initials: C
authors.lastname: Svaerke
authors.forename: Dóra Körmendiné
authors.initials: DK
authors.lastname: Farkas
authors.forename: Henrik Toft
authors.initials: HT
authors.lastname: Sørensen
mesh_terms: D015331:Cohort Studies; D003093:Colitis, Ulcerative / Q000150:complications*; D003424:Crohn Disease / Q000150:complications*; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology* / Q000209:etiology; D011379:Prognosis; D012307:Risk Factors; D054556:Venous Thromboembolism / Q000209:etiology*