Cologuard®, a new stool-DNA screening test for detecting colon cancer, is not as good at finding precancerous polyps as a colonoscopy, and, unlike colonoscopy, it can’t remove them. 

Cologuard has recently gained popularity because it is less invasive than a traditional colonoscopy test. Intrigued by lively ads with the sprightly Cologuard box jumping around on its blue legs, many adults aged 45 and older wonder if the test may work for them, allowing them to bypass a more invasive colonoscopy.

“Cologuard is a test that’s been on the market for a few years now,” says Brian Fritz, APRN, an Advanced Practitioner Registered Nurse at Gastroenterology Associates of SW Florida. “Some patients might have been exposed to it or have friends that have been exposed to it. Cologuard is a box test that gets mailed to your house, you collect the sample, and mail it back to the company.”

What are the Limits of the Cologuard Test?

There are some drawbacks to the Cologuard test, mostly involving its accuracy. Ninety-five percent of colon cancers begin as polyps. Stool sample tests are not as accurate as a colonoscopy when it comes to detecting precancerous polyps and lesions. 

According to a New England Journal of Medicine (NEJM) study, Cologuard misses more than 30% of polyps that will soon be cancer and 57% of polyps that may become cancer.

“There are some pitfalls with the test itself,” says Fritz. “The NEJM study data included 10,000 people. They had a colonoscopy, and they also submitted the Cologuard box test. Of those people that were found in the study, a fair number of people had colon cancer, large polyps, small polyps, or no polyps at all. It was a good representative sample of the general population.”

“Of the people who had colon cancer in that study, the Cologuard test missed 8% of them. Thirty percent of large high-grade dysplasia polyps were also missed with the test.”

The Cologuard test result should be interpreted with caution. A positive test result does not confirm the presence of cancer, and patients with a positive test result should be referred for diagnostic colonoscopy. Moreover, a negative test result does not conclusively prove the absence of cancer. 

Patients with a negative test result should discuss with their doctor when they need to be tested again. False positives and false-negative results can occur. 

In addition, eating certain foods before a Cologuard test, such as red meat, horseradish, or turnips, can result in a false-positive result. False positives can create unnecessary stress and worry while waiting for follow-up testing.

when should cologuard not be prescribedWhen Should Cologuard Not Be Prescribed?

Some people should not be prescribed Cologuard at all. The test is not approved for individuals at high risk of colorectal cancer, including those with conditions that increase the risk, such as:

  • A personal history of polyps
  • Inflammatory bowel disease
  • Chronic ulcerative colitis
  • Crohn’s disease

The Cologuard test should not be used if you have had adenomas, specific hereditary syndromes, or a personal or family history of colorectal cancer or polyps.

What is Cologuard?

Cologuard is the only stool-DNA screening test for detecting colon cancer that is approved by the Food and Drug Administration (FDA). The test looks for changes in your DNA that could indicate the presence of colon cancer. Cologuard also checks for precancerous polyps that might be present in your colon.

Most medical professionals recommend the use of colonoscopy for colon cancer screening for patients over the age of 50. Unfortunately, the procedure can be costly and feel invasive, which is concerning some physicians that patients are avoiding colon cancer screenings altogether. 

Colorectal cancer is the second leading cause of cancer death in the United States. The Centers for Disease Control and Prevention (CDC) reports that colon cancer killed more than 52,000 people in the United States in 2015. Screening is critical because when detected early, colorectal cancer is highly treatable. Early stages of colorectal cancer usually present no symptoms, which tend to appear as the disease progresses.

benefits of cologuardWhat are the Benefits of the Cologuard Test?

The Multi-Society Task Force on Colorectal Cancer recommends Cologuard as an acceptable second-line screening option. The task force concluded that physicians should recommend colonoscopy first. For patients who decline to have one, the fecal immunochemical test (FIT) test should be offered next, followed by second-tier tests such as Cologuard and CT colonography for patients who decline both of the first-line options.

The Cologuard test has several distinct benefits over other kinds of tests. It can be administered in the comfort of your home, which cuts back on time in the waiting room or the hospital. No prep is needed, you don’t have to take time off of work, nor do you need to change your diet, fast, or stop taking your medication before you take the test. 

Some people are hesitant about the colonoscopy procedure because it may require general anesthesia. Cologuard allows you to be screened without having anesthesia. However, if your Cologuard results are abnormal, the test should be followed up with a colonoscopy.

How Much Does Cologuard Cost?

Cologuard is covered by many health insurance companies, including Medicare. If you’re eligible (between the ages of 50 and 75) for colon cancer screening, you may be able to get Cologuard without any out-of-pocket expense. If you don’t have insurance or if your insurance won’t cover it, the maximum cost of Cologuard is $649. 

“If you refuse to do a colonoscopy, this is definitely a good test to at least have some screening for you and your loved ones,” says Fritz.

While there is general agreement that more U.S. adults over 50 need to be screened, increased awareness is needed about the benefits of colorectal cancer prevention. Moreover, the public needs to be made aware of the benefits of having a colonoscopy, as demonstrated by clinical evidence.


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