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Ask the Expert: Is New At-Home Test a Replacement for Colonoscopy?

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A reader of the Health After 50 newsletter asks: Can I use Cologuard as a replacement for a colonoscopy? William Dale, MD, PhD, Associate Professor of Medicine and Section Chief of Geriatrics and Palliative Medicine, Director of the Specialized Oncology Care and Research in the Elderly (SOCARE) Clinic, University of Chicago Medicine, Ill., answers:

Cologuard, a stool-based test that screens for colorectal cancer, was approved by the Food and Drug Administration last year. The test, which users perform at home and ship to a laboratory for results, detects microscopic amounts of blood in the stool as well as DNA that may indicate the presence of cancerous or precancerous growths.

This test’s appeal is that, unlike a colonoscopy, it’s noninvasive and it doesn’t require overnight emptying of the bowels by drinking an ill-tasting solution. Cologuard is available only by prescription from your doctor.

In a clinical trial of more than 10,000 people, Cologuard detected 92 percent of colorectal cancers, compared with 74 percent of cancers detected using the traditionally prescribed fecal immunochemical test (FIT), a similar home-based stool test. Cologuard also detected 42 percent of precancerous lesions versus FIT’s 24 percent detection rate. The downside was that Cologuard had considerably more false positives—when results wrongly suggest a problem—than FIT, leading to the need for invasive follow-up testing—primarily the previously mentioned colonoscopy.

In short, Cologuard is better at detecting colorectal cancer early when it can be most easily cured, but at the cost of the more invasive follow-up testing than the usual method. False positives, which are more common with Cologuard, are also associated with higher anxiety levels.

Cologuard doesn’t replace a colonoscopy, which gives your doctor a complete view of the entire length of your colon and rectum and the ability to remove any polyps that look as if they are, or could become, cancerous. The U.S. Preventive Services Task Force (USPSTF) recommends that people ages 50 to 75 at average risk for colorectal cancer be screened with a colonoscopy every 10 years.

People at high risk for colorectal cancer may need to be screened earlier than age 50 and more often than those at low to normal risk. People at high risk include those who have a personal or family his tory of colorectal polyps or colon or rectal cancer; inflammatory bowel disease, including Crohn’s disease or ulcerative colitis; or a genetic syndrome such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (Lynch syndrome).

If you’re not at high colorectal cancer risk and have been unwilling to undergo a colonoscopy because of its invasiveness or the uncomfortable bowel prep involved, Cologuard could very well be an option for you. But keep in mind that if the test comes back positive, which happens a bit more often than the current stool test (FIT), you’ll still need to undergo a colonoscopy to get a fuller assessment of your level of risk.

Though currently not part of the USPSTF’s screening guidelines, Cologuard is covered by Medicare every three years. 

 

Posted in Colon Cancer on May 22, 2016


Medical Disclaimer: This information is not intended to substitute for the advice of a physician. Click here for additional information: Health After 50 Disclaimer


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Health After 50 Alerts registered users may post comments and share experiences here at their own discretion. We regret that questions on individual health concerns to the editors cannot be answered in this space.

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It sounds like Cologuard has high sensitivity (low false negatives) and a little less specificity (more false positives). That is the basis for a good screening test which if positive, is followed up by a test that is very specific as well as sensitive...in other words, a colonoscopy. It seems to me that many people would prefer to avoid colonoscopies most of the time (as a result of a negative Cologuard test) using this new test.

Aside from the inconvenience and risks, it should be noted that colonoscopies are not 100% sensitive in that sometimes tumors or polyps are missed for example, when they are sessile or flat as opposed to pedunculated or on a stalk.

Posted by: AndyGpost | October 22, 2015 12:30 PM

The critical number in comparing this newer procedure is the number of false positives. In my opinion any percentage of false positive is sufficient to avoid this method. A colonoscopy is not that distasteful--even as you say. It's only temporary and any adult can easily sustain the discomfort. The key is this. So what if it indicates blood in the colon? You will not be happy till you do colonoscopy anyway to explore and remove any polyps that are there so what have you saved? There's no need to think we have found a "silver bullet". Either test is fine. If you're worried about something you need to go see a Doctor to get it anyway. If the Cologuard is so wonderful-- make it available over-the counter. Then try it--if you're worried about something --and take the result to your Doctor. Which you will need to do anyway! So, as I say, why introduce another unnecessary step.

Posted by: Mdk4130 | May 22, 2016 4:34 PM

Why would anybody want to do a highly invasive Colonoscopy (with risks) when there is an almost as sensitive home screening test available that you only have to do every 3 years?!? FIT is not sensitive at all and you would have to do it EVERY year (Guidelines). 0.3 % of patients are compliant with that. The biggest downside of Cologuard described in the article is the slightly higher false positive rate- That false positive rate is only 6.3%. That means out of 100 people who are doing the Cologuard test only 6 will get a false positive and will have to do a Colonoscopy without having anything. That is far better than 100 people having a Colonoscopies of which over 90 are unnecessary, right?

I would ALWAYS prefer a noninvasive test that detects Cancer almost as good as Colonoscopy to a Test that is bad at detecting Cancer and precancerous polyps (FIT).

The most important thing is that you get screened. I think Cologuard is a game changer.

Posted by: JJ | May 23, 2016 1:14 AM

Why would anybody want to do a highly invasive Colonoscopy (with risks) when there is an almost as sensitive home screening test available that you only have to do every 3 years?!? FIT is not sensitive at all and you would have to do it EVERY year (Guidelines). 0.3 % of patients are compliant with that. The biggest downside of Cologuard described in the article is the slightly higher false positive rate- That false positive rate is only 6.3%. That means out of 100 people who are doing the Cologuard test only 6 will get a false positive and will have to do a Colonoscopy without having anything. That is far better than 100 people having a Colonoscopies of which over 90 are unnecessary, right?

I would ALWAYS prefer a noninvasive test that detects Cancer almost as good as Colonoscopy to a Test that is bad at detecting Cancer and precancerous polyps (FIT).

The most important thing is that you get screened. I think Cologuard is a game changer.

Posted by: JJ | May 23, 2016 1:14 AM

I'm not convinced it's a "game changer". People talk about the preparation, about how it's "invasive"--so what! A hernia repair, now that's invasive. But colonscopy is as invasive as taking en enema. Big deal! I'll admit the preparation is a bugger, but once every 5 years is tolerated easily by a grownup. I remember getting a colososcopy and asking the nurse when are we going to get started? "Started", she said, "we're already finished." If Cologuard would say--"Hey, Buddy, you got 2 pre -cancerous polyps that should be removed" then I'll say it's a game changer.

Posted by: Mdk4130 | May 23, 2016 1:28 PM

I recently declined a colonoscopy in favor of Cologuard.

I previously had one colonoscopy. I was going to have another ; I had the initial appointment including a discussion with a G.I. specialist and a review of the patient instruction. I saw, among other things, that the high-fiber foods that I eat were forbidden before the procedure. That, the the other personal costs, and the availability of Cologuard, led me to cancel the actual procedure.

The personal costs of a colonoscopy include not only the unpleasant prep, but those of the procedure itself. On the day of the procedure, there's an extended fast if the appointment is in the afternoon. One must have someone -- a friend or relative, not a taxi driver -- transport one home. It requires a day off from one's occupation or usual activities.

The usual "twilight sleep" meds are powerful drugs with significant side effect risks. They screw with your memory -- not an attractive prospect for a 70-year-old. Do they really reduce pain and discomfort or do they just cause you not to remember afterwards, and, if the latter, is that OK? With sufficient insistence against doctor discouragement one can avoid the use of propofol or midazolam and, one assumes, not only experience the pain and discomfort but remember it. (The drugs make the procedure easier for the physician.)

The Cologuard stool collection system is designed and implemented well.

Posted by: brec | May 23, 2016 2:46 PM

Look, I don't think I'm trying to change anyone's mind. If Cologuard is so wonderful as you all say --it reduces unnecessary procedures and cost, it's not as unpleasant as is the other necessary preparation, it saves the Doctor's time, it saves you time, --OK--I got the point so why restrict it to getting it from a Doctor--you got to make an appointment to go see him--that takes more time and money anyway --Let's have it available over-the-counter. [ Will the manufacturer object? ] Make it low cost--let's say in the interest of everybody's health - Give me one reason why not! Then let anyone if so worried about colorectal cancer buy it--get the result--and be happy--or surprised --and still worried. Then go see the Doctor who will say I'll do a colonoscopy to put you at ease--or still worried. If you're over 85 forget about it.

PS: Is this site being sponsored by the manufacturer to get feed-back?

Posted by: Mdk4130 | May 23, 2016 3:09 PM

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