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What Are the Alternatives to Colonoscopy?

How good are the alternatives to colonoscopy, such as FIT or Cologuard, for detecting colorectal cancer? When should you start?

Colorectal cancer is the third most common type of cancer and the second leading cause of cancer death among American adults. If it is detected early, before it spreads, colorectal cancer can be treated effectively. That’s why gastroenterologists are adamant about the importance of screening for this condition. In 2019, about 67 percent of eligible people had gone through a screening procedure. The gold standard is colonoscopy, in which a specialist finds and removes growths called polyps. He or she does this during a visual inspection of the lining of the colon. Many people find preparation for colonoscopy (colon cleansing) arduous. In addition, though insurance usually covers the cost, some find the price too steep. Are there viable alternatives to colonoscopy? When should screening for colon cancer start?

When Do You Need Colon Cancer Screening?

A lot of people delayed routine tests and screening during the pandemic. Now, the US Preventive Services Task Force is urging everyone who is due for a colonoscopy to receive this life-saving preventive service (JAMA, May 18, 2021). In fact, they are moving the goal posts. Previously, doctors started doing regular colonoscopies once patients turned 50. This independent volunteer panel of experts in disease prevention is currently recommending that colon cancer screening start at age 45. This screening can be accomplished through colonoscopy or through alternatives to colonoscopy such as stool-based tests.

Preparing for a Colonoscopy:

Q. My question is about the prep for colonoscopy. My husband has had two; I have had one. It seemed to me that, although the prep was unpleasant for both of us, it was worse for me. Consequently, when it came time for my second colonoscopy, I opted for Cologuard instead, with my doctor’s agreement.

I weigh 120 pounds, and my husband weighs 210 pounds. Are any allowances made for such size differences when the prep solution is prescribed? I doubt it; it seemed like the product came in one standard size for each of us. Should allowances be made?

A. Periodic colonoscopies are an excellent way to detect colon cancer or, preferably, polyps even before they go rogue and turn into cancer. Since the polyps are removed during the procedure, they should not have a chance to cause further trouble.

The preparation for a colonoscopy is critical. The physician doing the procedure can see the polyps clearly only when the colon lacks all residue. This is why you “clean” your colon beforehand.

How Do You Prepare?

You are correct that pharmacies usually supply the bowel prep prescribed before a colonoscopy in a standard amount of powdered polyethylene glycol (PEG, an osmotic laxative), often with electrolytes, to be dissolved in four liters of water. The traditional instructions do allow for some personalization of dose. Patients are told to drink a cup every 10 minutes until the watery stool is completely clear. If you reached that point sooner than your husband, you could stop earlier.

Newer recommendations call for a “split-dose” approach. People are told to drink half the solution in 10- to 15-minute intervals starting in the late afternoon or early evening before the procedure. The second half is consumed in increments about four to six hours before the colonoscopy. Don’t give up on colon cancer screening; it can be a life saver.

Seeking Alternatives to Colonoscopy:

Q. More than a decade ago, I had a colonoscopy. Not liking that procedure, I chose to use Cologuard at the usual recommended 10-year retest. Both times, the tests were negative. Now, three years later, I asked my doctor to give me a referral to a gastroenterologist for my next Cologuard. She hemmed and hawed about the use of Cologuard, finally stating that her medical group is no longer using Cologuard because of “the inability to correlate the information provided by that test with the outcomes of a colonoscopy.”

My only option if I want a non-invasive screening would be to use an immunochemical fecal occult blood test yearly. Is this test reliable?

A. People at high risk of colorectal cancer due to family history or previous polyps should have regular colonoscopies. That is because the doctor removes any polyp he or she finds during the procedure.

How Reliable Are FIT and Cologuard as Alternatives to Colonoscopy?

Individuals at average or low risk may utilize one of the alternatives to colonoscopy. They could benefit from an FIT (fecal immunochemical test). This over-the-counter home test reveals blood in the stool. A study published in the Annals of Internal Medicine (Feb. 26, 2019) showed that such tests detect up to 80 percent of cancers.

A colonoscopy detects up to 95 percent of colorectal cancers. FIT can pick up as many as 91 percent of tumors, but it will also flag false positive cases. Anyone who tests positive on a FIT will need a follow-up colonoscopy.

Cologuard, based on detecting DNA from polyps, can also produce false positives (New England Journal of Medicine, April 3, 2014).

According to an early analysis of this technology,

“In asymptomatic persons at average risk for colorectal cancer, multitarget stool DNA testing detected significantly more cancers than did FIT but had more false positive results.”

One difference you should note: you should complete FIT screening every year. The doctors who developed Cologuard recommend that you use it every three years. We don’t know exactly why your doctor’s group has soured on Cologuard, as it seems that such alternatives to colonoscopy are viable for those who are not at high risk.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies..
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  • US Preventive Services Task Force, "Screening for Colorectal Cancer: US Preventive Services Task Force Recommendation Statement." JAMA, May 18, 2021. doi:10.1001/jama.2021.6238
  • Imperiale TF et al, "Performance characteristics of fecal immunochemical tests for colorectal cancer and advanced adenomatous polyps: A systematic review and meta-analysis." Annals of Internal Medicine, March 5, 2019. DOI: 10.7326/M18-2390
  • Imperiale TF et al, "Multitarget stool DNA testing for colorectal-cancer screening." New England Journal of Medicine, April 3, 2014. DOI: 10.1056/NEJMoa1311194
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