The researchers investigated the effect of the increased use of azathioprine and 6-mercaptopurine for inflammatory bowel disease (IBD) on the risk of lymphoma.
They reported their results in the January issue of Gastroenterology.
All patients with IBD at a single tertiary-care medical center, who developed lymphoma between 1985 and 2000, were identified. The pathologic features of the lymphoma, including presence of Epstein-Barr virus, were determined.
The patients were divided into two 8-year periods (1985-1992 and 1993-2000), corresponding with the introduction of azathioprine and 6-mercaptopurine in 1993.
A total of 18 patients with lymphoma were identified, 6 in 1985-1992 and 12 in 1993-2000.
| Azathioprine and 6-mercaptopurine were introduced in 1993.
| Gastroenterology |
Six of 18 lymphomas occurred in patients treated with azathioprine or 6-mercaptopurine, all in 1993-2000.
Some 7 patients developed Epstein-Barr virus-positive lymphoma (1 in 1985-1992, 6 in 1993-2000).
The team found that 5 of 7 Epstein-Barr virus-positive lymphomas occurred in patients treated with azathioprine or 6-mercaptopurine, compared with 1 of 11 Epstein-Barr virus-negative lymphomas.
Approximately 1200 patients with IBD were treated with these agents in 1993-2000.
Gerald A. Dayharsh, of the Mayo Clinic, Rochester, Minnesota, concluded on behalf of his colleagues, "Treatment of inflammatory bowel disease with azathioprine or 6-mercaptopurine appears to be associated with a small increased risk of Epstein-Barr virus-positive lymphoma."