The risk of lymphoma and immunomodulators in patients with inflammatory bowel diseases: Results from a population-based cohort in Eastern Europe

Abstract Background and aims Prior studies suggest a small but significantly increased risk of lymphoma in adults with inflammatory bowel disease (IBD), especially in patients treated with thiopurines. No data was available from Eastern Europe. The aim of this study was to analyze the incidence of lymphomas as related to drug exposure, in a population-based Veszprem province database, which included incident cases diagnosed between January 1, 1977 and December 31, 2008. Methods Data from 1420 incident patients were analyzed (UC: 914, age at diagnosis: 36.5 years; CD: 506, age at diagnosis: 28.5.5 years). Both in- and outpatient records were collected and comprehensively reviewed. The rate of lymphoma was calculated as patient-years of exposure per medication class, of medications utilized in IBD. Results Of the 1420 patients, we identified three patients who developed lymphoma (one CLL, two low-grade B-cell NHL including one rectal case), during 19,293 patient-years of follow-up (median follow-up: 13 years). All three patients were male. None had received azathioprine or biologicals. The absolute incidence rate of lymphoma was 1.55 per 10,000 patient-years, with 3 cases observed vs. 2.18 expected, with a standardized incidence ratio (SIR) of 1.37 (95% confidence interval [CI]: 0.44–4.26). No cases have been exposed to either azathioprine or biologicals. Conclusions The overall risk of lymphoma in IBD was not increased; only three cases were seen in this population-based incident cohort over a 30-year period. An association with thiopurine exposure was not found.