Crohn's and Colon Cancer: The Risk

I have Crohn's disease and my father died of cancer in his intestinal tract. Does this mean that I have two risk factors for intestinal or colon cancer, or just one? The thought led me do some research.

Most authorities agree that after having Crohn's disease (or ulcerative colitis) for a long time (translated in most articles as over 8 years of severe symptoms), you have an increased risk of getting colon cancer, or even cancer of the small intestine. One physician writes "Colorectal cancer is a significant clinical problem for patients with long-standing.... Crohn's disease" (Itzkowitz, 1997, abstract). He adds that some more recently noted factors, such as primary sclerosing cholangitis (an inflammation of the liver's bile ducts that is often associated with inflammatory bowel disease, or IBD), folate (or folic acid) deficiency, and a genetic predisposition to colon cancer (a family history), also affect a Crohn's patient's likelihood of getting colon cancer. Other sources, such as medicinenet.com and intellihealth simply say that for Crohn's patients there is an increased risk of cancer of the colon or intestines.

But what is the risk? The physicians at the Mayo Clinic (see citation below) say that "more than 90% of people with inflammatory bowel disease never develop cancer (p.7; my emphasis). The Crohn's and Colitis Foundation of America (CCFA) in their brochure "Understanding Colorectal Cancer," reiterate that statistic, and go on to explain that two risk factors can increase your risk of cancer with an IBD. They are how long you've had it (8 to 10 years, according to the brochure) and "the extent of the colon that is affected by colitis" (p. 3). They note that there is some variation in statistics between different studies, but that after 10 years, the risk of getting colon cancer increases at a rate of 0.5% per year for both Crohn's disease and ulcerative colitis.

The CCFA brochure seems to fall on both sides of the Crohn's equals colon cancer debate. First they say that if you have an IBD you should be concerned about developing colon cancer, noting that with an IBD your risk is five times as great as for people without Crohn's or ulcerative colitis. They go on to say that you should feel safe, because you are still more likely not to get cancer than you are to get it, noting the Mayo Clinic's statistic that more than 90% of people with Crohn's or ulcerative colitis never develop cancer.

All of this has left me feeling that my risk of getting colon cancer is higher than that of people without Crohn's disease, and without a family history of it, but that it isn't a foregone conclusion that I will get it and in fact it is far more likely that I won't. But there is no getting around the fact that there is a statistical link between having an IBD and developing colon cancer. It means that I should be careful about getting regular checks, and take steps to prevent the development of cancer.

(Resources used: Itzkowitz, Steven H. MD: 1997: Inflammatory Bowel Disease and Cancer, in the Gastroenterology Clinics of North America; www.nlm.nih.gov/medlineplus/ency/article/000285.htm#Definition; "Understanding Colorectal Cancer" a brochure from www.ccfa.org, no date provided; www.intelihealth.com/IH/9339/11024.html by the faculty of Harvard Medical School, updated July 27, 2006; www.medicinenet.com; http://www.mayoclinic.com/health/crohns-disease/DS00104 )