Imuran and 6mp (basically the same drug) have been used for many years in Crohn's with good results for most patients. There have been a number of long term studies showing that the cancer risk is very minimal, mostly related to lymphoma, which can also be a result fo the runaway inflammatory condition associated with uncontrolled disease. The dosages used in Crohn's treatment are very low as well. Remember that it can take months for this medication to reach full potency. The most common side effect is leuk
openia (suppressed white cell count) but that is seen in only 10% or so. Your doctor should have you on regular blood count monitoring to watch for that, and it is reversible by simply stopping the meds or lowering dose.