My GI informed me that there have been rare cases where patients taking Azathioprine and Remicade have developed some form of lymphoma. I was on both for a short period of time before he pulled me off of Azathioprine.
I haven't done any research on the topic myself but it may be something you could ask your GI.
32 yr old male
Diagnosed with Crohns in 1994 (lower bowel/ileum)
Medication history: prednisone, azacol, sulfasalazine, cipro
Current Medications: entocourt (periodically-as needed), Remicaid, flagyl
Surgeries: 2002 (remove fistula), 2004 (6" of ileum removed)