Cancer of the small intestine is quite rare.
After 10 years, 1 in 500 people with Crohn's will get small bowel cancer. After 20 years, 1 in 45 people with Crohn's disease will get small bowel cancer. Now add the increased likelihood of getting colon cancer. Now add the possibility of getting lymphoma from azathioprine or TNF-alpha inhibitors. Suddenly, the likelihood of getting cancer from Crohn's doesn't seem so remote.
I'm not saying that we should be hiding under our beds, living in constant fear of cancer. But we should remain constantly vigilant and have a high index of suspicion to ensure that, if it does end up causing cancer, we can nip it in the bud. Sticking one's head into the sand and ignoring the epidemiological data isn't going to help.