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 (EXAS), 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 (PFE) 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 (MDT) about esophageal cancer.

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  • Reply to Carol’s reply to Heleb —

    Carol, your post that you had to pay the deductible etc says to me that you have regular Medicare without a Medicare supplement.

    My Supplement pays most such costs.

    So, again, the cost for each person is unique, depending on exactly what Medicare plan they have. And yes, location factors in too I guess.

    • I’m a year away from Medicare. I’m still under my employer’s coverage as a retiree but that will combine with Medicare when I’m eligible. I was just giving the poster an idea of the cost so he could do the math from there. One of my doctors’ wives also had a false positive with Cologuard. He said she called Cologuard and ‘gave them a piece of her mind.’ lol. I doubt it did any good but I’m sure she felt better!

    • I guess your area could determine the cost but mine was $4600. My insur pd for the Cologuard which was false positive by the way. The Cologuard was considered my 10-year ‘screening.’ The colonoscopy was then considered diagnostic—not screening—so I got stuck with the insur deductible and 80% of the remaining balance; those bills should be arriving any day now. So, do your homework and call Medicare if you can’t get answers online. I saw my primary dr this week and he was somewhat annoyed at the whole Cologuard debacle of false positives saying, “they’ll get away with it for as long as they can.” My sentiments exactly. Best of luck to you!

    • Heleb, due to the number of different Medicare plans, I think you need to call Medicare and ask them that question yourself with your own personal info.

      There’s regular Medicare, and people with that may or may not have a Supplement; plus each Supplement is unique. Then there are Medicare Advantage Plans — some are HMO’s and some are PPO’s.

      You need to find out what your costs would be depending on exactly what you have for Medicare.

  • I can’t believe we’re in the 21st century and medical engineering for a lower GI exam is medieval. We can perform CT and MRI scans, but we can’t do anything better than an invasive tedious colonoscopy or shipping our excrement for a questionable diagnosis? Medical engineering should be deeply ashamed.

  • Many of your colleagues do not agree with your assessment of Cologuard. In fact I have read several opinions of gastro Drs. who say if a person carries no risk factors for colon cancer they themselves recommend the Cologuard test. I am no Dr., but from all I have read there may be a small chance that the Cologuard test could miss something, but that also happens with colonoscopies, plus colonoscopies carry their own risks. I had a bad experience with a colonoscopy myself due to one of the drugs that was administered. You being a Dr. know better than anyone that anesthesia can be very detrimental, but we as patients are learning that also. You guys don’t always tell the whole story when you are advocating for particular procedures for fear that the patient will decline having it done. I didn’t get this from just my own research, I have friends who are Drs. and have been told by them that what I say is true.

  • If the Cologuard mistakes are random, then just do a second test and the probability of missing a true cancer will go down a lot. A third one will virtually eliminate it. The added cost would be well worth it for many who have no desire for a traditional colonoscopy.

    The point here is to get people who will do nothing to do something. Don’t let the perfect be the enemy of the very good.

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