Cologuard Screening vs. Colonoscopy: Which Is Indicated?

Doctor in white coat and rubber gloves holds endoscope for colonoscopy

When actor Chadwick Boseman died in August 2020 at the age of 43, fans around the world were shocked that a man so vital could have died at home. Initially, rumors of a “poisoning” swirled throughout the media, but only because the actor had been tight-lipped about the true cause of his passing. The wonderfully talented young star, well-known for his starring role in the movie Black Panther, had been diagnosed with Stage III colon cancer in 2016. He continued working while receiving treatment, but his disease unfortunately advanced to Stage IV, eventually killing him.

Chadwick Boseman was well-loved by fans. His legacy will last long beyond his years, but perhaps his early diagnosis of colon cancer will bring awareness to a disease that is increasing in younger Americans while simultaneously decreasing slightly in older Americans due to screening techniques. The American Cancer Society expects in 2020 alone that 104,610 new cases of colon cancer will be diagnosed, as well as 43,340 new cases of rectal cancer.

Due to the increased incidence of younger patients being diagnosed with colorectal cancer, the American Cancer Society has upgraded screening guidelines for the detection of this type of cancer to begin at the age of 45.

What type of screening, you ask? That remains a particularly important question.

What is Cologuard?

Anyone owning a television or Smartphone has seen the cute Cologuard box dancing around encouraging (mostly health conscious men) to ask their physicians about Cologuard. The ads have become a successful marketing ploy geared to men who may know that colon cancer is the third leading cause of cancer deaths in the United States, but who would rather skip a colon prep and procedure entirely. The ad is pitched to focus on convenience and ease of use for busy professionals.1

Cologuard needs to be ordered by your physician, but there is also a form on the company’s website that you can fill out to send to your physician as a request. At present, Cologuard is the only FDA approved stool test that checks for abnormal DNA and traces of blood in the stool that may be caused by precancerous polyps and/or colon cancer. If you are in an age bracket eligible for screening and have insurance, you may be able to receive the test without out-of-pocket expenses. If not, the test is expensive (maximum cost on the website is stated at $649).

The box comes with a collection chamber for the toilet, syringes and a plastic probe for stool collection, preservative, and notes. Once the samples have been collected and the information completed, all items should be returned to the box, and the completed test returned to the lab within 24 hrs.1

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When is Cologuard appropriate?

The target demographic for the Cologuard test is described as “people who have an average risk and should be tested for colon cancer on a regular basis.” This definition leaves a lot of room for loopholes. What is known about Cologuard testing is that false negative and false positive results occur. The incidence of false positive testing is ~13%, meaning blood is detected in the stool and subsequent screening is negative. False negative results on Cologuard (which would carry far more significant implications) are ~8%. Colonoscopy does not carry the risk of false negatives, which is important for individuals with increased risk factors to remember.2

If you do get a positive Cologuard test result, a colonoscopy will be recommended, as it is impossible to determine if a positive test result is a “false” result or an indication of clinical findings until further testing is completed.3

What about colonoscopy?

For numerous reasons, colonoscopy remains the gold standard in diagnosing colorectal abnormalities. Colonoscopy uses a flexible, lighted tool called a colonoscope to view the entire colon and remove cancerous and precancerous growths called polyps when they are viewed. Ninety-five percent of colon cancers begin as polyps, and the earlier these are detected and removed, the better the outcome for the patient.3

Colonoscopy requires preparation. The procedure involves risk as it is invasive and requires sedation. Although complications to the procedure are rare, the types that may occur are the following: an adverse reaction to the sedative used during the procedure, bleeding from the site where a biopsy was taken (often a polyp or other abnormal tissue), or very rarely, a tear in the colon or rectal wall, which would require immediate surgical repair.

Colonoscopy also requires time off work, and dietary preparation as well as a prep. The colon needs to be completely emptied for adequate visualization of the bowel during the exam, which usually requires a liquid diet for a full day before the exam, and a liquid prep (or laxative) the night before the exam. Many find drinking an entire gallon of bowel prep to be arduous, but my peers and I have found it goes down easier if it is kept refrigerated and consumed in a glass with a cover and straw, and poured over ice. This will keep vomiting at bay.

For patients with comorbidities, and those on multiple medications, these issues need to be discussed with the gastroenterologist in-depth when the procedure is scheduled so the patient knows what medications to take or discontinue prior to the procedure, especially for diabetic, heart medications, or blood thinners, etc. Following the procedure, patients will be groggy, and will not be allowed to drive themselves home. If a polyp or abnormal tissue was removed, a special diet may be recommended for a brief period.

Follow-up will depend on results. For normal findings, a colonoscopy may be repeated in 10 years. For those with findings of polyps, another colonoscopy may be needed in 5 years. If cancerous lesions are found, the patient would be referred to an oncologist.4

Which screening test is appropriate for you?

One area of concern with gastroenterologists has been the increase in referrals from physicians who have patients with “positive” results from Cologuard tests. Why? Medicare and insurance providers will pay for an initial colon screen, but they may balk at covering a second, unless a specific GI diagnosis exists. If a patient falls into the realm of positive Cologuard results, they do not know if they have disease until they have another exam. Unfortunately, the exam may not be covered by insurance. What do they do? Wait and take another Cologuard if the colonoscopy is refused? Maybe not…4

The primary care provider may choose to order a FIT test (fecal immunochemical test) that looks for blood in the stool from the large intestine. This is another screening possibility. The test kit is easy to use, and all supplies come contained in a kit that can easily be mailed back. The kit can also be obtained for people with minimal resources through the American Cancer Society for as little as $25 online.

In summary, patients should consider all options when deciding on a plan for colorectal cancer screening. They should discuss both pros and cons with their healthcare provider, with appreciation of their specific risks and hereditary make-up. Should they decide that convenience works for them? Or do they need the gold standard, even if it requires a break from work and routine?

Chadwick Boseman died much too young, leaving us mourning a hero who embodied considerably more than a screen star. Although he remained private about his terminal disease, it has been written that he visited many children with cancer during his final months. While he will live on as a movie icon, he should also serve as a reminder that colorectal cancer can take the youngest and best of us without appropriate screening. In 2020, it is expected that 53,200 Americans will die from the disease.

Let’s do our best to bring this statistic down.


  1. “What is the Cologuard test?” Watson, K. medically reviewed by Yamini Ranchod, Ph.D., M.S., Updated August 3, 2020, Healthline Media.
  2. “The truth about Cologuard tests.” March 27, 2019, Gastroenterology Consultants of San Antonio, 210-614-1234.
  3. “Cologuard vs. Colonoscopy: Know the differences.” March 02, 2020, 2020 Franciscan Health inc. 877-285-6920.
  4. “Colorectal cancer screening: science should trump convenience.” Gunaratnam, N., September 24, 2018, STAT news, 2020.

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