title: Increased risk of intestinal cancer in Crohn's disease: a meta-analysis of population-based cohort studies.
abstract: OBJECTIVE
  The risk of intestinal malignancy in Crohn's disease (CD) remains uncertain since risk estimates vary worldwide. The global CD population is growing and there is a demand for better knowledge of prognosis of this disease. Hence, the aim of the present study was to conduct a meta-analysis of population-based data on intestinal cancer risk in CD.
  
  
  METHODS
  The MEDLINE search engine and abstracts from international conferences were searched for the relevant literature by use of explicit search criteria. All papers fulfilling the strict inclusion criteria were scrutinized for data on population size, time of follow-up, and observed to expected cancer rates. STATA meta-analysis software was used to perform overall pooled risk estimates (standardized incidence ratio (SIR), observed/expected) and meta-regression analyses of the influence of specific variables on SIR.
  
  
  RESULTS
  Six papers fulfilled the inclusion criteria and reported SIRs of colorectal cancer (CRC) in CD varying from 0.9 to 2.2. The pooled SIR for CRC was significantly increased (SIR, 1.9; 95% CI 1.4-2.5), as was the risk for colon cancer separately (SIR, 2.5; 95% CI 1.7-3.5). Regarding small bowel cancer, five studies reported SIRs ranging from 3.4 to 66.7, and the overall pooled estimate was 27.1 (95% CI 14.9-49.2).
  
  
  CONCLUSIONS
  The present meta-analysis of intestinal cancer risk in CD, based on population-based studies only, revealed an overall increased risk of both CRC and small bowel cancer among patients with CD. However, some of the available data were several decades old, and future studies taking new treatment strategies into account are required.
authors.affiliation: Department of Medical Gastroenterology C, Herlev University Hospital, Copenhagen, Denmark.
authors.forename: Tine
authors.initials: T
authors.lastname: Jess
authors.forename: Michael
authors.initials: M
authors.lastname: Gamborg
authors.forename: Peter
authors.initials: P
authors.lastname: Matzen
authors.forename: Pia
authors.initials: P
authors.lastname: Munkholm
authors.forename: Thorkild I A
authors.initials: TI
authors.lastname: Sørensen
mesh_terms: D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000628:therapy; D015897:Comorbidity; D016001:Confidence Intervals; D003424:Crohn Disease / Q000175:diagnosis* / Q000453:epidemiology* / Q000628:therapy; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D007414:Intestinal Neoplasms / Q000175:diagnosis* / Q000453:epidemiology* / Q000628:therapy; D008297:Male; D016017:Odds Ratio; D011379:Prognosis; D018570:Risk Assessment; D016019:Survival Analysis