Thiopurines Boost Lymphoma Risk Three-Fold, But Wait

According to a study reported at the annual meeting of the American College of Gastroenterology, the continuous use of thiopurines in patients with ulcerative colitis (UC) boosts the risk of developing non-Hodgkin's lymphoma three-fold.

However, while that may sound dramatic, the absolute risk for lymphoma remains low enough that experts don't believe these results should warrant patients discontinuing medication, especially if they derive a lot of benefit from it.

This retrospective cohort study included data from 36,826 patients with UC treated in the Southeast Louisiana Veterans Health Care System in a 10-year span. Patients were divvied into one of three groups:

1. Continuous users of thiopurines (2 percent)
2. Discontinuous users of thiopurines (11 percent)
3. Nonusers of thiopurines (87 percent)

After a median follow-up of six years, investigators determined the incidence rate of lymphoma to be 2.8 cases per 1,000 patient-years in those using thiopurines continuously. That rate is compared to 0.7 and 0.8 per 1,000 patient-years for the other two groups respectively. These rates worked out to a hazard ratio of 3.2 for continuous users compared to the other groups.

These data are fairly consistent with the existing data on the use of thiopurines and lymphoma. The findings do not add anything new to the discussion, but they do add weight to the ongoing notion that immunosuppressive drugs can increase one's risk of developing lymphoma.