Azathioprine is an invaluable drug for the long term treatment of IBD. Many patients enjoy prolonged remissions. Its metabolite 6-mercaptopurine has similarly beneficial effects. One of the main anxieties in the use of azathioprine is the incidence of side effects. Patients are familiar with the need for repeated blood tests to pick up bone marrow suppression and other effects such as malaise or hepatic or pancreatic damage may affect in all as many as 20% of sufferers. In patients who remain well on these drugs, the decision of when to stop them is always difficult. A French study some years ago suggested that the relapse rate after 4 years was such that this was a suitable interval at which to cease treatment. However, no general agreement has been reached.
Such immunosuppressive therapies may contribute to the development of a malignant disease of the lymphatic system in a number of ways. Decreased immune responses to viruses such as the Epstein Barr virus may contribute to the development of Lymphoma and furthermore these drugs may cause direct damage to DNA rendering it unstable leading to possible mutations.
However, the overall risk of such developments has been unclear. The American Journal Gastroenterology, in Nov 2013, contained a report on a retrospective nationwide study of patients with Ulcerative Colitis showing that patients had a four-fold increase in the risk of lymphoma whilst being treated, compared to patients who had not been treated with azathioprine or 6-MP. The risk increases gradually for successive years of therapy but discontinuing treatment reduces the risk.
For these reasons it may be sensible to avoid prolonged courses of these drugs and perhaps the four years suggested by the French workers represents a sensible mile stone. Unfortunately Ulcerative colitis is not usually amenable to treatment with diet, but nutritional treatment of Crohn’s disease avoids all risk of the subsequent development of lymphoma and it is sensible for all patients with proven Crohn’s disease to consider whether they may not be better suited to an appropriate diet which may also lead to prolonged remission. (Kahn et al Gastroenterology 2013 145 1007-15)
This article was first published on the original crohns.org.uk blog. Research has moved on since, so please check current advice with your IBD team.