A recent study provides some good news for those using thiopurines (6-mercaptopurine and azathioprine) (Gastroenterol 2013; 145: 166-75).
Using the observational cohort enrolled in the French CESAME study (Cancers et Surrisque Associe aux Maladies Inflammatoires Intestinales En France), the authors followed 19,486 patients with IBD. 60.3% had Crohn’s disease, and 30.1% were receiving thiopurine therapy. The study period was 2004-2007. At the start of the study, 2841 patients (14.6%) had long-standing extensive colitis.
Among patients with long-standing extensive colitis, the hazard ratio for colrectal high grade dysplasia and cancer was 0.28 for those who received thiopurine therapy compared with those who never received thiopurine therapy.
Thus, this prospective study showed that while colorectal cancer (CRC) was increased in IBD patients with long-standing colitis, this risk was less among the subset who were treated with thiopurines. Some previous studies have not found a reduction in CRC risk, though they may have been underpowered and biased as these studies came from referral centers.
The authors also cautioned that more than 1/3rd of CRC cases occurred in those without extensive colitis which may necessitate a lower threshold for screening colonoscopy.
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