Issue 18

Clinical Question

Does the long-term use of either aminosalicylates (5-ASA) or thiopurines alter the risk of developing colorectal cancer (CRC) in IBD?

Editor’s Bottom Line

5-ASA exposure is associated with a lower risk of colorectal cancer in patients with IBD, although it is unclear from this analysis whether this benefit reflects control of inflammation or direct chemoprevention.

Reference

Carrat F, Seksik P, Colombel JF, et al; CESAME Study Group. The effects of aminosalicylates or thiopurines on the risk of colorectal cancer in inflammatory bowel disease. Aliment Pharmacol Ther. 2017 Feb;45(4):533–41. https://www.ncbi.nlm.nih.gov/pubmed/27995656

Synopsis

CESAME was a prospective cohort of 19,486 patients with IBD enrolled from 2004–2005 and followed until 2007. From this dataset, patients with a diagnosis of CRC (cases) at any time before 2004 or until 2007 were matched with controls (1:2) for gender, age, IBD subtype, year of diagnosis, and extent of colitis. Demographics, disease history, medications, surgeries, and endoscopy reports were reviewed. Smoking habits and primary sclerosing cholangitis (PSC) were also noted. Medication exposure was measured in the year of the cancer diagnosis. Propensity scores were used to compensate for potential prescribing bias in favour of 5-ASA in patients at higher risk for CRC.* Relationships between exposure to treatments and CRC incidence were explored via multivariate conditional logistic regression with propensity scoring.

Within the 144 cases and 286 controls, medication exposure in the year of cancer diagnosis was similar between cases and controls. Mean duration of 5-ASA exposure was 8–10 years and did not differ significantly between cases and controls. Similarly high percentages of cases and controls (97% and 95%) had undergone a colonoscopy within the 5 years prior to cancer diagnosis. Among patients who received 5-ASA during the calendar year of cancer diagnosis, approximately 80% of both cases and controls had been exposed for >2 years. 5-ASA provided a protective effect during the calendar year of cancer diagnosis (OR=0.587, 95% CI: 0.367–0.937, P=0.0257, but thiopurines had no significant effect (OR=0.762, 95% CI: 0.432–1.343, P=0.3468). Study limitations included inability to adjust for lifestyle factors and chronic inflammation.

* Velayos FS, Terdiman JP, Walsh JM. Effect of 5-aminosalicylate use on colorectal cancer and dysplasia risk: a systematic review and metaanalysis of observational studies. Am J Gastroenterol. 2005;100:1345–53. https://www.ncbi.nlm.nih.gov/pubmed/15929768

Details

Study Design: Retrospective nested case control study
Funding: Ferring Pharmaceuticals
Allocation: Stratified by incidence of colorectal cancer (CRC)
Setting: France
Level of Evidence: 2b (Oxford Levels of Evidence)

The summary and conclusion in this issue of E-mentoring in IBD pertains to the manuscript(s) being reviewed, and should be considered in the context of what is already known surrounding the topic and incorporated into practice as deemed appropriate by the individual learner.