Lymphoma in inflammatory bowel disease: Baseline risk and influence of immunomodulators

There has been controversy over whether inflammatory bowel disease (IBD) patients are at increased risk of developing malignant lymphoma relative to the general population. Large population-based studies from several locales have shown that there is not an increased risk of lymphoma in IBD compared to the general population, with two exceptions. Some but not all referral- or hospital-based studies have suggested an increased baseline risk of lymphoma in IBD; however, these studies must be discounted because referral bias may have influenced the results. The bulk of the evidence suggests no increased baseline risk of lymphoma in IBD. Although several case series have detected a low frequency of lymphoma in IBD patients receiving purine analogues, one series reported a markedly increased risk among those treated with azathioprine, methotrexate and cyclosporin. Moreover, there are several reports of Epstein-Barr virus-positive lymphomas, which are likely related to immunosuppression, occurring in patients receiving these medications. Whether immunomodulatory medications are associated with an increased risk of lymphoma in IBD remains unclear.