Irritable Bowel Syndrome patients not at more risk of colon cancer, polyps

Patients with irritable bowel syndrome are at no greater risk of having polyps, colon cancer or inflammatory bowel diseases than healthy people undergoing colonoscopies, according to new research published in the American Journal of Gastroenterology.

“Patients and doctors get nervous about the symptoms of irritable bowel syndrome (IBS),” says William D. Chey, M.D., professor of Internal Medicine at the University of Michigan Medical School. “They think the symptoms represent something more sinister.”

“This study should reassure doctors and patients that typical IBS symptoms are not indicators of a more serious disease,” he adds.

Chey was the lead author on the study, the largest prospective evaluation of the results of colonoscopies in patients with irritable bowel syndrome.

IBS symptoms include recurrent episodes of abdominal pain or cramping in connection with altered bowel habits. The condition affects 10 to 20 percent of the U.S. population and is more common among women than men. Many of those afflicted never seek treatment.

IBS patients often undergo colonoscopies because physicians are particularly concerned about missing colorectal cancer or inflammatory bowel diseases like ulcerative colitis or Crohn’s disease, Chey says. Roughly a quarter of all colonoscopies performed in the U.S. are for IBS-related symptoms.

This research shows that it is unnecessary to order colonoscopies for IBS patients, unless they show other alarming symptoms like unexplained weight loss or anemia, bleeding from the GI tract, or have a family history of colon cancer, inflammatory bowel disease or celiac disease, says Chey, who also is director of U-M’s Gastrointestinal Physiology Laboratory and the Michigan Bowel Control Program.

“Lay people and doctors overuse colonoscopies, which are very expensive procedures, in patients with typical IBS symptoms and no alarm features. Of course, patients over the age of 50 years or who have alarm features should undergo colonoscopy to screen for polyps and colon cancer.” Chey says.

Chey’s research also showed that a small percentage of IBS patients older than 35 (2.5%) had an unusual disease called microscopic colitis. Microscopic colitis can masquerade as IBS in patients with diarrhea and is important to diagnose because it is treated differently than IBS, he says.

March is colorectal cancer awareness month. Not counting skin cancers, colorectal cancer is the third most common cancer found in men and women in this country. The risk of a person having colorectal cancer in their lifetime is about 1 in 19. Go to U-M's Cancer Center site for more information about colorectal cancer.

Written by Mary F. Masson