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Rates and characteristics of postcolonoscopy colorectal cancer in the Swedish IBD population: what are the differences from a non-IBD population?
  1. Jessica Stjärngrim1,
  2. Anders Ekbom1,
  3. Ulf Hammar2,
  4. Rolf Hultcrantz1,
  5. Anna M Forsberg1
  1. 1 Department of Medicine, Solna (MedS), Karolinska Institutet, Stockholm, Sweden
  2. 2 Institute of Environmental Medicine (IMM), Karolinska Institutet, Stockholm, Sweden
  1. Correspondence to Dr Anna M Forsberg, Department of Medicine, Solna (MedS), Karolinska Institutet, Stockholm S 17176, Sweden; anna.forsberg{at}


Objective The rate of postcolonoscopy colorectal cancer (PCCRC) is considered a key quality indicator of colonoscopy; little is known about PCCRC in IBD.

Design A population-based cohort study of colonoscopies in Sweden from 2001 to 2010 was conducted. Individuals with a colorectal cancer (CRC) detected within 36 months after a colonoscopy were identified and stratified on UC, Crohn’s disease (CD) or non-IBD. The CRCs were classified as detected CRCs (dCRC) (0–6 months) or as PCCRCs (6–36 months). PCCRC rates were calculated by the number of false negative/(the number of true positive+the number of false negative) colonoscopies. Poisson regression analysis was employed to examine the association between PCCRC and IBD (CD and UC) diagnosis, age, gender, location, time period and comorbidities.

Results We identified 348 232 colonoscopies in 270 918 individuals. Of these, 27 123 were performed on 14 597 individuals with CD, and 51 572 were performed on 26 513 individuals with UC. There were 13 317 CRCs in the non-IBD group, 133 in the CD group and 281 in the UC group. The PCCRC rate in the CD group was 28.3% and 41.0% in the UC group. The RR for a PCCRC was 3.82 (95% CI 2.94 to 4.96) in CD and 5.89 (95% CI 5.10 to 6.80) in UC, compared with non-IBD. The highest risk was observed among rectal cancer location in CD and in younger individuals with UC.

Conclusion The high rates of PCCRC in young patients with UC and for rectal cancer location in CD might affect future performance of IBD surveillance.

  • cancer prevention
  • inflammatory bowel disease
  • colonoscopy
  • colorectal cancer
  • cancer epidemiology

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  • Contributors Planning the project: all authors. Data collection: AMF and UH. Statistical analysis: AMF, UH and JS. Analysis of the results: all authors. Drafting the manuscript: JS, AMF and UH. Revision of the manuscript: AMF. Critical reading and approving the manuscript: all authors. All the authors have approved the revised manuscript.

  • Funding Financial support was provided through the regional agreement on medical training and clinical research (ALF) between Stockholm County Council and Karolinska Institutet by the Swedish Society of Medicine and by the Swedish Cancer Society.

  • Competing interests None declared.

  • Ethics approval The study was approved by the local ethical committee at Karolinska Institutet (Dnr: 2015/690-31/2).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Patient consent for publication Not required.