Incidence and risk factors for lymphoma in a single-center inflammatory bowel disease population.

Aims: Previous studies on the risk of lymphoma in inflammatory bowel disease (IBD) have yielded conflicting results. We aim to determine the incidence and risk factors for lymphoma in a large IBD population.

Methods: Patients with lymphoma were identified from a single-center IBD database. The standardized incidence ratio (SIR) of lymphoma was estimated using data from the Surveillance, Epidemiology and End Results (SEER) registry. Risk factors for lymphoma were determined by comparing cases with a matched IBD control group.

Results: Eleven lymphomas were identified among 3,585 IBD patients during an average of 8.4 years of observation. Three patients were excluded. In the remaining eight, median age at diagnosis was 47 years and mean IBD duration was 20 years (range 7.5-45 years). The SIR for lymphoma was 1.6 [95% confidence interval (CI) 0.6-3.0], and for non-Hodgkin lymphoma (NHL), 1.5 (0.3-2.8). Three lymphoma patients (38%) received prior immunomodulators and two (25%) received biologics, versus 57% and 39% in the control group, respectively (P = 0.4). No correlation was seen with tobacco exposure, disease duration, use, or dose or duration of immunosuppressive therapy.

Conclusions: In this IBD cohort, risk of lymphoma was not increased compared with the general population. Risk of lymphoma was not associated with any demographic or therapy-related factors.