It’s been difficult for TV watchers to avoid the sprightly Cologuard box jumping around on its spindly blue legs, beckoning viewers to take an at-home, stool-based test for colorectal cancer. Joining in the multimillion-dollar national public relations and advertising blitz by Cologuard’s maker, Exact Sciences, are singer/actor Harry Connick Jr., golfer Jerry Kelly, and the Green Bay Packers.

Celebrity endorsements of health care products are nothing new. As early as 1958, Milton Berle’s jokes about Miltown, an antidepressant, were promoted to gossip columnists by the drug’s maker. Today’s direct-to-consumer marketing makes Berle’s efforts seem tame in comparison. Many such campaigns, including the one for Cologuard, seem like public health campaigns that are barely recognizable for what they really are: product advertisements.

The increased attention to Cologuard has resulted in more than 1.3 million people using the test. And with the recent announcement of a marketing partnership with Pfizer that will increase the size of the sales force promoting Cologuard to primary care physicians and hospitals, this may be just the beginning.


Make no mistake: Increased screening for colorectal cancer is important. It’s the third most common type of cancer (excluding skin cancer) in the United States, and is expected to kill more than 50,000 Americans this year.

But many gastroenterologists like me are concerned about the referral cases we’re seeing for follow-up colonoscopies triggered by positive Cologuard tests, especially those in which Cologuard should not have been prescribed in the first place. Many of us are also concerned that an outsized focus on convenience is overshadowing serious limitations of the test.

For me, it’s personal. I will never forget trying to find the right words to comfort my uncle who was dying from colon cancer — a disease I have spent my professional life trying to prevent.

There are four main ways to screen for colorectal cancer. (Screening means trying to find hidden cancer in seemingly healthy people.) Colonoscopy is the gold standard. It uses a flexible, lighted tool called a colonoscope to view the entire colon and remove cancerous and precancerous growths called polyps if they are detected. CT colonography uses a CT scanner and computer programs to create a three-dimensional view of the inside of the colon and rectum that can be used to identify polyps or cancer. Another method is the fecal immunochemical test (FIT), which checks stool for tiny amounts of blood given off by polyps or colorectal cancer. Cologuard tests stool for tiny amounts of blood as well as for certain abnormal sections of DNA in cells shed by cancer or polyps that end up in the stool.

In 2014, researchers funded by Cologuard’s maker published in the New England Journal of Medicine results of a study of 10,000 patients comparing three methods of colorectal cancer screening. Screening colonoscopy was better at finding cancer and pre-cancerous polyps than both Cologuard and the FIT test. Cologuard found 93 percent of the cancers detected by screening colonoscopy. That’s a great result, but when we’re talking about cancer, missing 7 percent is a big deal. That means Cologuard could fail to detect colorectal cancer in 1 out of every 13 people who use the test — a significant number considering that more than a million people have used it and many more will likely use it.

Ninety-five percent of colon cancers begin as polyps. Cologuard is not as good at finding pre-cancerous polyps and, unlike colonoscopy, it can’t remove them. According to the NEJM study, Cologuard misses more than 30 percent of polyps that will soon be cancer, and 57 percent of polyps that may become cancer.

I got deeply concerned about this when I read news reports that Exact Sciences stock jumped double digits in May 2018 because new screening guidelines from the American Cancer Society potentially increased the market for Cologuard by 20 million Americans when it lowered the minimum age for colorectal screening from age 50 to age 45.

Don’t get me wrong. Cologuard is a good screening test. In fact, I was one of the physicians who provided patient data for its initial validation study. 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 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.

Some people should not be prescribed Cologuard at all. It 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, or familial adenomatous polyposis; or a family history of colorectal cancer or polyps.

The task force ranked colonoscopy in the top tier of screening tests because it is the only test that not only detects colorectal cancer but also prevents it by removing polyps during the procedure. It is the only test that is appropriate for people who have risk factors such as a personal or family history of colorectal cancer or polyps.

Almost 1 in 6 people who use the Cologuard test will have a positive result that suggests the presence of colorectal cancer. They will no doubt worry they have colon cancer while scheduling and preparing for the recommended follow-up colonoscopy. For almost half of them (45 percent), the colonoscopy will show they do not have cancer.

Individuals with a positive Cologuard test who are covered by Medicare may face a costly bill because insurance covers 100 percent of the cost of colonoscopy as a preventive screening test, but a follow-up colonoscopy for a positive Cologuard is considered a diagnostic or therapeutic service and may not be fully covered.

Colorectal cancer is the second leading cause of cancer death in the United States, behind lung cancer, but the survival rate is very high if it is found early. Preventing cancer is even better than finding it early. If our goal is to prevent colorectal cancer, then finding, quantifying, localizing, and removing polyps is the most effective strategy.

Every time I diagnose colorectal cancer, I feel like the system has failed.

Some day we may have a simple blood, saliva, or stool test that can detect colorectal cancer and polyps better than colonoscopy. There may even be medications to remove the cancer or dissolve polyps. When that day arrives, I will prescribe that new screening test because the science is sound and it is in the best interest of my patients. Until then, I will counsel physicians and their patients to choose science over convenience. That choice should be screening colonoscopy, the only test that can both detect and prevent colorectal cancer.

Naresh Gunaratnam, M.D., is a gastroenterologist and research director at Huron Gastroenterology in Ypsilanti, Michigan; chief medical officer of Lean Medical Technologies; and a speaker for Medtronic about esophageal cancer.

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  • I had three negative occult fecal samples and then a positive cologuard. So I went for the colonoscopy, which I had been dreading mostly because of the prep involved. The prep has significantly changed, and I drank Miralax and Gatorade which was perfectly acceptable. I even was allowed to eat some plain pasta for a light lunch the day before. So the prep was MUCH less horrible than I had heard. The procedure itself was so minimal I didn’t even realize it had happened when I woke up. They found one tiny non-cancerous polyp. So I don’t really know if the cologuard was a false positive or not, and neither do the docs. I am grateful for the results, obviously, and I can rest easy for about 10 years.

    My complaint now is the outrageous cost that all of this involved. Cologuard costs $650– exacerbated by the constant advertising?? Colonoscopy costs around $5000, including the site, the GI doc and the anesthesiologist. Luckily, my insurance is good, so I only paid a relatively low co-pay. But what do the people who don’t have insurance or whose insurance doesn’t pay for it do? They just do not get the tests, and they get sick! This is the main problem now, in my mind. We need to have a better way to ensure good health (pun intended). The author’s comments don’t address this at all, and the amount of money involved is the disgraceful state of health care in our country today.

  • The promotion of Cologuard as an alternative to colonoscopy is unconscionable. Since the vast majority of colon cancer starts with polyps, it is important to find those polyps well in advance and remove them, before they are cancerous. As the doctor said, Cologuard offers no such visibility. Even if it did, another procedure would be necessary to remove them. As for the risk involved of such an “invasive procedure,” try ignoring colon cancer and having to have your colon removed, and the accompanying cancer treatment. You may survive if you are lucky. I had an aunt and a brother-in-law who died from colon cancer, unnecessarily. Now everyone in my family has colonoscopies, regardless of the (boo-hoo) inconvenience. The cost should be less of an issue these days, as most responsible insurance companies offer coverage. If you are worried about the risk, pick a doctor who has performed many, many of them and can nearly do them in his sleep. But whatever you do, don’t put it off. Colon cancer is a terrible way to die.

  • Just got a positive result and am scheduled for colonoscopy this week. Your statement following, “Almost 1 in 6 people…” suggest 55% of those with positive cologuard results have colon cancer. Am I understanding you correctly?

  • Just to add…
    I have read Dr. Hadler’s thoughts on colon cancer screening. It appears for those who are not at high risk, the left colon is the most likely site for positive polyps and can be viewed with a flexible sigmoidoscopy at a much lower risk than colonoscopy. Thoughts?

  • I’ll admit to confusion. The comment seems to neglect the risk of colonoscopies. And you do seem to oversell…selling past the close.

    No sale.

  • Once again, we have a Gastroenterologist trumpeting the virtues of their INVASIVE diagnostic test over anything else on the market. It’s called GREED. Gastro docs fear losing market share and $$$ to a brand new NON-INVASIVE test that demonstrates 94% specificity (only a 6% false positive rate) for those in the 50 – 64 year old age group.

    The US Preventative Services Task Force has NEVER designated the non-invasive stool DNA screening test known as Cologuard as a “second line screening option”. That is an bold faced outright lie.

    The science for Cologuard is not only sound, it is on very solid ground given the “Deep C” results that were published in the New England Journal of Medicine. Cologuard is FDA approved and included in the USPSTF colon cancer guidelines, which make it 100% covered by commercial insurance. The current Cologuard assay ALSO includes the FIT test, which the author of this article conveniently leaves out.

    • and yet wouldn’t it be awesome Mike, if I hadn’t taken the cologuard test, believing I didn’t have any risk factors and therefor it was a waste of time an money? Now, I’ve receive a positive result that could be 45% incorrect?

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