P415. Low risk of lymphoma in inflammatory bowel diseases in Western Hungary. Results from a population-based incident cohort

L. Lakatos1, B.D. Lovasz2, A. Horvath3, T. Pandur1, Z. Erdelyi1, G. Mester4, M. Balogh4, I. Szipocs5, C. Molnar6, E. Komaromi7, P.A. Golovics2, L.S. Kiss8, P. Lakatos2

1Csolnoky F. Province Hospital, 1st Department of Medicine, Veszprem, Hungary; 2Semmelweis University, 1st Department of Medicine, Budapest, Hungary; 3Csolnoky F. Province Hospital, Department of Pediatrics, Veszprem, Hungary; 4Grof Eszterhazy Hospital, Papa, Hungary; 5Municipal Hospital, Tapolca, Hungary; 6Magyar Imre Hospital, Ajka, Hungary; 7Municipal Hospital, Varpalota, Hungary; 8Semmelweis University, I.st. Internal Medicine Clinic, Budapest, Hungary

Background: 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 is available from Eastern Europe. Our aim was to analyze the incidence of non-Hodgkin lymphoma in relation to drug exposure in the population-based Veszprem province database, which included incident patients diagnosed between January 1, 1977 and December 31, 2008.

Methods: Data of 1420 incident patients were analyzed (UC: 914, age at diagnosis: 38.9 SD 15.9 years, median follow-up: 12 years; CD: 506, age at diagnosis: 31.5 SD 13.8 years, median follow-up: 11-years). Both in- and outpatient records were collected and comprehensively reviewed. Continuous thiopurine exposure was recorded in 45.8% (n = 232) of CD and 7.3% (n = 67) of UC patients. The rate of lymphoma was calculated in patient-years of exposure for each class of medications utilized in IBD.

Results: Of the 1420 patients we identified three patients who developed lymphoma (one Hodgkin, two low-grade B‑cell NHL including one rectal case), in 18,066 patient-years of follow-up (median duration of follow-up 12 years per patient). All three patients were males. One CD patient diagnosed with UC at the age of 51 years developed NHL 3 years later and he is alive 3 years after the diagnosis of the lymphoma. In addition lymphoma developed in two UC patients; the first 60 years at UC diagnosis and 76 years at diagnosis of Hodgkin disease died one year later unrelated to the lymphoma and the second 71 years old at the UC diagnosis and developed NHL at the age of 76 years and is still alive 7 years after the lymphoma diagnosis. None have received azathioprine or biologicals. The absolute incidence rate of lymphoma 1.66 per 10,000 patient-years compared to the expected rate of 1.19 per 10,000 patient-years, with a standardized incidence ratio (SIR) of 1.46 (95% confidence interval [CI] 0.42–5.07) in males 3.43 per 10,000 patient-years compared to the expected 1.28 (SIR: 2.67, 95%CI: 0.85–8.31) and an association with azathioprine or biological exposure was not found.

Conclusions: The overall risk of lymphoma in IBD is low, with only three cases seen in this population-based incident cohort over a 30-year period. Similarly, we did not find an association with tiopurine exposure.