Risk of lymphoma in inflammatory bowel disease

OBJECTIVE: Inflammatory bowel disease with a subsequent diagnosis of non-Ho dgkin's lymphoma has been reported. There is concern that the risk of devel oping lymphoma will rise with increasing use of immune modifier therapy. We determined the risk of non-Hodgkin's lymphoma in an U.S. population-based inception cohort, and evaluated the association between inflammatory bowel disease and lymphoma in our referral practice. METHODS: The records of all incidence cases of inflammatory bowel disease i n Olmsted County, Minnesota, between 1950 and 1993 were reviewed for the di agnosis of lymphoma. Standardized incidence ratios (observed/expected) were used to estimate relative risk. In addition, the clinical features and out comes of all patients with inflammatory bowel disease and lymphoma seen at Mayo Clinic between 1976 and 1997 were reviewed. RESULTS: Among 454 county residents diagnosed with inflammatory bowel disea se, a single non-Hodgkin's lymphoma occurred in a patient with Crohn's dise ase. No cases were seen with ulcerative colitis. The estimated relative ris k of lymphoma was 2.4 in Crohn's disease (95% confidence interval, 0.1-13), 0 in ulcerative colitis (0-6), and 1.0 in inflammatory bowel disease overa ll (0.03-6). Between 1976 and June 1997, 61 patients with inflammatory bowe l disease and lymphoma (approximately 0.41%) were seen in the referral prac tice. In four patients with Crohn's disease (13%), potential neoplastic ris k factors were identified-therapeutic radiation in 1, and use of purine ana logs in 3 (median length of use, 11 months). CONCLUSIONS: Our population-based cohort study demonstrated that the absolu te risk of non-Hodgkin's lymphoma remains quite small (0.01% per person-yea r). This risk may not exceed that in the general population. In our referra l practice, immune modifier therapy could be potentially implicated in only 5% of cases of lymphoma occurring in the setting of inflammatory bowel dis ease. (Am J Gastroenterol 2000;95:2308-2312. (C) 2000 by Am. Coll. of Gastr oenterology).