I have. I developed Stage 1 colon cancer in the sigmoid as well as anal area. My doctor believes the cancer developement was the direct result of two factors: 1) unchecked inflammation led to the growths (meds weren't working, and I was too scared to move up to Remicade, Methotrexate) and 2) The type of Crohn's I have makes me more susceptable.
He removed the cancer and then gave me four rounds of medium strength chemo-pills, infusions, and shots (Arava, Methotrexate). Not horrible, but not a cake-walk. I tested cancer-free 6 months later, and it's been two years. I just had another colonoscopy which found a polyp in the same area, but thank God is was benign.
I don't have any statistics; sorry. I do remember the doctor saying your risk goes up significantly after you've been diagnosed 20 years; mine was at 17 years after diagnosis. Quite honestly he said alot of things the day he told me but after the word Cancer my brain shut down for about 4 days afterward. I really wished I had another person with me on that visit.
CCFA might have statistics, and more info. Hope this helps!