Colon Cancer and IBD: Understanding the Link

Colon cancer, the third most common type of cancer in the United States, is a serious health threat for men and women over 50. However, if you are of the one million Americans living with an inflammatory bowel disease (IBD), you face a higher risk for colon cancer than the average person.

IBD, which includes Crohn's disease and ulcerative colitis, is a disorder of the gastrointestinal tract. Inflammation can occur anywhere along the gut, but it typically affects the lining of the colon when the intestinal wall becomes irritated and sometimes ulcerated. People with this condition experience cramps, bloating and a wide range of bowel problems. There is, of yet, no known cause or cure for IBD but many patients achieve some improvement in their condition with medication or dietary changes. No one knows why IBD ups the risk of this cancer, but it is believed to be a function of chronic inflammation.

Still, it is important that those living with IBD understand their risk for colon cancer and regularly monitor their health. Steven Itzkowitz, MD, a professor of medicine, and Thomas Ullman, MD, an assistant professor of medicine, both from the Mt. Sinai School of Medicine in New York City, explain the prevalence of colon cancer and medical options available to people with IBD.

How high is the risk of colon cancer for people with IBD?
THOMAS ULLMAN, MD: You are at increased risk of developing colon cancer if you have long-standing and extensive ulcerative colitis or long-standing and extensive Crohn's colitis.

STEVEN ITZKOWITZ, MD: After having colitis for about eight years, a person's risk of colon cancer starts to go up by about a half a percent to 1 percent each year. IBD is thought to be the third-highest risk factor for colon cancer, after two hereditary syndromes: familial polyposis and Lynch syndrome.

How is colon cancer screened in patients with IBD?
STEVEN ITZKOWITZ, MD: Once you've had your colitis for about eight years, even if you have relatively few symptoms, you should be going for regular colonoscopies about every one to two years; some people say every one to three years. The colonoscopy itself turns out to be quite well tolerated. We have very good anesthetics now where people literally wake up and say, "When are we going to get started?"

How is colon cancer diagnosed in patients with IBD?
STEVEN ITZKOWITZ, MD: With patients who have inflammatory bowel disease, we may find polyps or raised growths during the colonoscopy, but there can also be precancerous or sometimes even cancerous changes that are flat and almost invisible. So we do multiple biopsies, sampling the tissue throughout the colon to try to detect these areas that are otherwise invisible.

THOMAS ULLMAN, MD: The samples are examined [under a microscope] by the pathologist to see what the cells look like and to determine the presence or absence of dysplasia, which are precancerous changes in the colon.

How are precancerous changes and colon cancers treated in people with IBD?
STEVEN ITZKOWITZ, MD: Dysplasia has different gradations: low-grade dysplasia and high-grade dysplasia. If an expert pathologist tells you have a high-grade dysplasia, there's a 45 to 65 percent likelihood that there is already cancer in the colon or will be in the near future. If you only remove a part of the colon that you think has the area of cancer, there is a very high likelihood that cancer will crop up in the future. So, most physicians would recommend that the whole colon should be removed. With low-grade dysplasia, there is a little bit more controversy. But, because of our inability to see all cancers before they become problematic in people with IBD, many doctors will recommend that you consider removing the colon.

That's why the stakes are a little bit higher for people with IBD. The surgery for colon cancer or dysplasia in inflammatory bowel disease means taking out the entire colon and rectum, whereas, in the general population, if you found a cancer or a precancerous polyp, you only have to remove that one little segment of the colon that's affected.

What surgical options are available?
STEVEN ITZKOWITZ, MD: New surgical techniques, available in the last decade, are more conducive to an active lifestyle. If we have to remove the colon and the rectum, we can create an internal pouch out of the end of the small intestine and bring that down to the muscles at the lower sphincter. The person can still be able to [go to the bathroom] normally.

Occasionally, people will need an end ileostomy, where the colon and the rectum are removed and the end of the intestine is brought out through the skin to an external appliance. Sometimes that's a better operation.

Can colon cancer be prevented in people with IBD?

STEVEN ITZKOWITZ, MD: With IBD patients, there are a few different compounds that may lower the risk of colorectal cancer. The one that has been proven to be the most efficacious is ursodeoxycholic acid (USRO), or Actigall. [This drug may prevent cancer by reducing levels of a carcinogenic substance called deoxycolate and bile acid in the colon.] So far, this has only been looked at in the high-risk group of IBD patients who also have primary sclerosing cholangitis, an inflammation of the bile ducts in the liver. In this small group of people, about 5 to 10 percent who take USRO seem to have a lower rate of cancer and dysplasia.

If you look at all IBD patients, not just the sclerosing cholangitis group, there seems to also be some evidence that the 5-aminosalicylate compounds (otherwise known as mesalamine) reduce the risk of colon cancer and dysplasia.

Then, there's folic acid, a safe, inexpensive vitamin. We don't have good scientific proof that it lowers colon cancer or dysplasia risk, but there's some circumstantial evidence that it may work in IBD, and there's pretty good evidence in the non-IBD population, that it seems to lower the risk of colon cancer.

We have to just remind our patients that even if they take these medicines, they still need to come for regular colonoscopy.

What is your colon cancer screening advice for people with IBD?

THOMAS ULLMAN, MD: We actually do a very good job of preventing cancer in ulcerative colitis and in Crohn's colitis. So the first thing that I would tell patients is, "Don't worry early on in the course of disease." Build a strong alliance with your gastroenterologist and then when the time comes—after eight years—do yourself the favor and have your annual colonoscopy.

Sphere: Related Content