Colon Cancer and IBD

If you have IBD, are you at an increased risk for colon cancer?

A patient undergoes a coloscopy under hypnosis, Argentan hospital, France.
 Burger/Phanie/Getty Images

Colon cancer awareness has been raised to new levels, which is great because screening saves lives. It is recommended that anyone at risk get tested via a colonoscopy. Risk factors include a family history of colon cancer, being over 50 years of age, and having inflammatory bowel disease (IBD). But take heart, the good news is that more than 90% of IBD patients never develop colon cancer.

Factors Affecting Your Risk

For people with ulcerative colitis, there are two factors affecting the risk of developing colon cancer. The first factor is that risk increases after 8 to 10 years of having ulcerative colitis. The second is the extent of the disease in the colon. Patients with disease only in the rectum have the lowest risk. Having only part of the colon involved carries an intermediate risk. The greatest risk is for people whose entire colon is diseased (called pan-colitis). There is also a similar risk of colon cancer for those with Crohn's disease, but comprehensive studies have not been performed.

Symptoms of colon cancer include:

  • Change in bowel habits
  • Diarrhea, constipation, or feeling that the bowel does not empty completely
  • Bright red or very dark blood in the stool
  • Narrow stools
  • Gas pains, bloating, fullness, and cramps
  • Unexplained weight loss
  • Chronic fatigue
  • Vomiting

The Approximate Risk

The results of different studies vary, but in general, the risk of colon cancer for people with IBD increases by .5% to 1% yearly approximately 8 to 10 years after diagnosis.

Other studies have shown that people with IBD are five times more likely to develop colon cancer than the general public. Colon cancer doesn't distinguish between active disease and remission. Patients whose IBD has been quiet have the same risk as those who have more active disease.

The list of colon cancer symptoms closely overlaps those commonly found in a flare-up of IBD, so it can be difficult to distinguish between a flare-up and colon cancer without doing tests.

A blood test and rectal exam might be the first steps in determining the cause of the symptoms.

Screening For Colon Cancer

For patients with longstanding ulcerative colitis, a colonoscopy may be done to rule out the possibility of cancer. Colonoscopies will need to be repeated at regular intervals as determined by the gastroenterologist. After 8 to 10 years of ulcerative colitis, the doctor may recommend a colonoscopy every year or every two years.

It is important for IBD patients to make yearly appointments with their gastroenterologist, and to report any changes in disease activity. The gastroenterologist can make a more informed assessment of the risk of colon cancer in each patient based on history, other risk factors, and the extent and duration of IBD.


Crohn's and Colitis Foundation of America. "Bringing to Light the Risk of Colorectal Cancer among Crohn’s & Ulcerative Colitis Patients." 2012. 28 Aug 2012.

The National Women's Health Information Center. "Crohn's Disease." Dec 2005. 30 Apr 2014.