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Colonoscopy Isn't First Choice for Many

< Apr. 11, 2012 > -- Given the option of having a stool test or a colonoscopy to screen for colorectal cancer, most people would go with the stool test.

Photo of woman talking with her doctor

That's the conclusion of a new study that looked at the two tests and people's reluctance to get screened.

Although a colonoscopy is considered the "gold standard" in colorectal cancer screening, not everyone who should have one follows through and gets one.

"The best test is the one the patient actually performs," says lead researcher John Inadomi, M.D., at the University of Washington in Seattle. Just because doctors hold up colonoscopy as the better screening test, "we should not assume that all patients prefer colonoscopy," he says.

Quick and easy

The stool test, called the fecal occult blood test (FOBT), looks for blood in the stool. It's simple to do and takes little preparation. A positive result from the FOBT requires follow-up testing to find out if the cause is cancer.

A colonoscopy's advantage is that any cancerous or precancerous polyp found during the procedure can be removed right then.

The drawback for many people is the preparation. For a successful colonoscopy, the bowel must be completely clean, a process that requires a day or two of fasting and taking laxatives. Many patients also don't like being sedated, and there can be complications, particularly a puncture of the intestine cause by the instrument, Dr. Inadomi says.

Given a choice

For the study, published in the Archives of Internal Medicine, the researchers followed 997 men and women who had either been assigned to or given a choice between a colonoscopy or an FOBT.

Within a year, 58 percent of participants had undergone one of the two tests. Most of the screening tests were FOBTs. Only about 38 percent of people who chose or were assigned to a colonoscopy actually had one. More than 67 percent of those who chose or were assigned to an FOBT had one.

Whites were more likely than other ethnic groups to have a colonoscopy. African-Americans had the lower rate of colorectal cancer screening in general, at 48 percent. The highest screening rates were in Asians, at 61 percent, and Latinos, at 63 percent.

Other tests

Theodore Levin, M.D. , at Kaiser Permanente Medical Center in Walnut Creek, Calif., says that people have several alternatives to colonoscopy, including a virtual colonoscopy and sigmoidoscopy.

"If we want to raise our screening rates, then we need to offer people choices other than colonoscopy," Dr. Levin says.

For more information on health and wellness, please visit health information modules on this website.

Occult Blood Test vs. Colonoscopy

Two of the main screening tests for colorectal cancer are the fecal occult blood test (FOBT) and the colonoscopy. Here's a closer look at each:

Stool test

The FOBT looks for hidden - also called occult - blood in your stool. For the test, you place several small samples of stool on an FOBT sample card. Typically, you take two samples from each of three consecutive stools at home and mail or take them to your health care provider's office for testing. The lab uses a chemical reaction to find any blood in the samples.

Blood in the stool can be caused by many conditions, including colorectal cancer. If the lab finds blood, you will probably need additional testing to locate the source of the blood. It might be caused by a polyp, hemorrhoids, inflammatory bowel disease, or diverticulosis.

Certain foods or medicines can affect the FOBT, so you should follow your health care provider's instructions on how to prepare for the test.


In a colonoscopy, your doctor uses a colonoscope, a long, slender, flexible lighted tube, to look for polyps. If your doctor finds a polyp, he or she can remove it and send it to the lab to check for cancer.

You'll need to prepare for a colonoscopy several days ahead by taking laxatives or enemas to thoroughly clean out your colon. A colonoscopy can be uncomfortable, so your doctor will usually give you an intravenous medication to make you feel sleepy during the procedure. A colonoscopy takes about 30 minutes; longer if a polyp is removed.

The American Cancer Society recommends that screening for colorectal cancer begin when you turn 50. If you're at average risk, you should have an FOBT every year and a colonoscopy every 10 years.

Always talk with your health care provider to find out more information.

Online Resources

(Our Organization is not responsible for the content of Internet sites.)

American Cancer Society - Colorectal Cancer Screening Tests

Archives of Internal Medicine - Adherence to Colorectal Cancer Screening

National Cancer Institute - What You Need to Know About Cancer of the Colon and Rectum