A systematic review 1 including 6 cohort studies with a total of 3891 subjects with inflammatory bowel disease (IBD; ulcerative colitis or Crohn's disease) was abstracted in DARE. The overall incidence of lymphoma (SIR 4.18, 95% CI 2.07 to 7.51, with a total of 11 cases of lymphoma) and the incidence of non-Hodgkin lymphoma (SIR 3.92, 95% CI 1.78 to 7.47, with a total of 9 cases of non-Hodgkin lymphoma) were increased among IBD patients compared with the general population. An increased risk of lymphoma was observed in IBD patients treated with azathioprine or 6-mercaptopurine compared to IBD patients who had not received this therapy (RR 2.92, 95% CI 1.05 to 8.13, 3 studies). The dosages of azathioprine ranged from 1.65 mg/kg per day to 106 mg/day for, and from 12.5 to 100 g/day for 6-MP. The mean duration of treatment was between 12.5 months and 4.4 years. It is not possible to fully exclude the possibility that the increased risk of lymphoma is associated with the severity of the disease, rather than being caused by the medications. Even if the increased risk is entirely attributable to the medications, it is unlikely to outweigh the potential benefits of these medications for most patients.
Primary/Secondary Keywords