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.

Leave a Comment

Please enter your name.
Please enter a comment.

  • I cannot get a colonoscopy because the prep makes me violently vomit (ibs) and then I end up in the ER because it turns to dry heaves and I get so weak, I can’t even hold my head up. If something new comes out, that will work for me, PLEASE EMAIL ME. Thanks, Jane, age 68

  • Another false positive here. I am a low-risk patient with one perfect colonoscopy 10 yrs ago, so my doctor thought I’d be a good candidate for Cologuard. I had a ‘positive’ test result. I immediately consulted a GI doctor and had a diagnostic colonoscopy. Absolutely nothing was found. I have lovely colored pictures of my pristine colon with not even a polyp, not even a bump anywhere. I asked the doctor how Cologuard reports its test results—if they were specific as to what was found such as DNA from cancer cells or blood….or is it just rubber-stamped “Positive” or “Negative.” He said it is just rubber-stamped. I am furious. I had two months of stress thinking the worst and STILL had to go through the colonoscopy anyway. Why this thing is even on the market is beyond me. All I can say is it must be all about the money.

  • Just like a colonoscopy prevents colon cancer by finding precancerous cells before they progress to colon cancer, WATS3D helps identify precancerous cells so they can be removed before they can progress to Esophageal cancer.

  • Your comments suggest the inherent bias that you have. Gastroenterologists are trained to do colonoscopies. Performing colonoscopies is a big money business, garnering millions of dollars annually for gastroenterologists. Anything that might reduce that is going to be looked at with skepticism by the money makers. I’m not suggesting that GI docs are completely motivated by money, but good economic research suggests all doctors, subconsciously or otherwise, tend toward procedures or testing when it is beneficial for their bottom line.

    In addition, you didn’t mention that the US Preventive Services Task Force has identified testing such as Cologuard as equivalent to colonoscopy. In addition, for patients who will not get colonoscopies because of arduous nature of the procedure are not getting screened. Cologuard provides an opportunity to perform effective screening without the loss of time (going through the prep and the procedure can cause people to lose 2 or more days of work–Cologuard: none). Also, while colonoscopy is supposed to be done every 10 years, if there are any concerning lesions, then often patients will have to return in 3 or 5 years for repeat surveillance of lesions that often never become cancer–and they can run into the same insurance issues for “diagnostic” colonoscopies.

    Your argument is a bit one-sided, and doesn’t identify the significant benefits of this procedure. It’s non-invasive, so no risk of perforation of the colon (while low risk, it does happen to patients). It can be done without any colon preparation, rather mailing a stool sample to the company. The “pre-cancerous” lesions found by colonoscopy and not found by Cologuard were also mostly ones that never progressed to a cancerous state or were identified later and treated without any impact on the overall prognosis (ie. treatment was just as effective at a later date than if it had been identified at time zero).

    I wouldn’t be so quick to diminish the benefit of this procedure. And I have no financial interest in promoting Cologuard. I have partners in my practice who do colonoscopies, so if anything it would be to my benefit to promote. I don’t get any financial remuneration for promoting or getting my patients to use Cologuard. I use it as an option that I discuss with my patients because it is a good, reliable, effective screening tool that will save lives–and there is no sufficient indication that it is so inferior to colonoscopy that it should be “second tier.”

    Finally, you also neglected to point out that there is another option that is considered equivalent. Flexible sigmoidoscopy is a procedure infrequently used in the US, but considered first line in many countries (ie. England, Canada) for screening. It uses the same scope, but only goes up part of the colon. All research has shown no difference in its effectiveness for colon cancer screening, yet its use in the US has diminished. This is because it doesn’t generate as much money. It costs less to do, doesn’t require any anesthesia/sedation. It is considered as effective because cancerous lesions found further up the colon where the colonoscopy goes haven’t been as effectively treated, even when found early, as the ones found in the last 70cm or so of the colon. Hence, identifying colon cancer early in the ascending colon, transverse colon early doesn’t help the patient as much. We do colonoscopies because they generate more revenue. Canadians and Brits receive flexible sigmoidoscopies because their doctors don’t get paid more to do colonoscopies, so they’re not incentivized to do so. They stick with what is effective medically and economically.

    Patients should be allowed to see the full scope of options with as minimal of bias as possible. Cologuard should be presented for what it is. Not perfect, but a great option for most people who warrant colon cancer screening.

    Thad Barkdull, MD

    • My mother was dead within four months after a sigmoidoscopy. Her cancer was on the other side of her colon. I do realize that Cologuard has its place, but the fact of a high incidence of false positives and then the insurance problem is definitely something to consider when weighing your options. I think this article did a good job of presenting it as an option but with more information about it so people can make a choice. I don’t think this article was biased at all. People need all this information to make a choice, and now knowing about the false positives and then the insurance problem is very helpful. Since I have a family history, the Cologuard test is not an option for me anyway, but my brother used it as a replacement for a colonoscopy because his doctor said it would be okay. He chose to do this because he was having trouble scheduling time off from work for a colonoscopy. I sent him this article because I thought he needed to know about this and I told him I thought he should definitely get the colonoscopy just to make sure.

  • I am in my mid 50s and my doctor has told me it is very important to have a colonoscopy. However, I have a heart arrhythmia and take daily medication. The warnings on the preps have me totally fearful that the prep will literally kill me from sudden cardiac arrest. Is there a safe prep for arrhythmia patients?

  • I just found out that since I am 47 (not 50), my insurance company will not cover a colonoscopy. I’m considering paying for it out-of-pocket, but it will be very expensive. As an alternative, I’m also considering colo-guard. It seems like it is better than doing nothing. But the false positives are, of course, alarming.

    • Hi Adam, If you are 47, you must have some reason for wanting a colonoscopy at your young age. I would advise against Cologuard. I have talked to sooo many people who have had false positives and the wife of one of my doctors is one of them! She had a positive Cologuard test, then a follow-up colonoscopy which was negative. I talked to a woman today, same thing. Mine was positive as well so now I have to go through a colonoscopy even though I don’t think for a second that I have colon cancer. My last colonoscopy was clean. If you want/need to pay out of pocket for anything, skip the Cologuard and save $649. It raises more qustions than it answers.

  • SO ANGRY. This product should be taken off the market. Because of a positive result, I now have to pay for my colonoscopy that would have been covered 100% as a wellness screening. NO CANCER. I trusted my doctor when I was told it was a free screening. Loved the bill from Exact Sciences for lab work.$649. Only lab in the country to test this and of course it is out of network. Now I have ALL the other bills to pay that come with the colonoscopy because of the positive result. This product is a load of shit.

    • I’m in the same boat. Just found out my insurance will not pay for a colonoscopy considered diagnostic after they paid for a Cologuard. I’m going to be stuck with a huge bill!

  • I JUST NOW received a call from my dr’s office that my Cologuard test came back positive. I don’t think for a second that I have colon cancer as my last colonoscopy yielded no polyps and was perfectly normal. Now I wished I’d never used Cologuard and went straight for my colonoscopy screening which I’m going to have to do anyway. I didn’t realize there was such a high rate of false positives for this DNA screening!

  • After years of neg. results…this new test came back positive. Worried, I paid the $102 out of pocket for the laxative, underwent the colonoscopy and…surprise, surprise…no polyps. This was a total ripoff and waste of my time in my opinion. Would advise my friends not to waste their time and money.

  • I took this test and have a hx of hemorrhoids noted the next day a tiny amt blood on the TP bright as in the past .All I thought was well I hope that little amt doesn’t screw up my test ie already sent it out. Iwasn’t to shocked it came back positive but no one not even the lab could tell me the DNA result just that small tube was positive I found that baffling to say the least. I now have to pay a huge Clonosc. charge. I took the colog.because I blew out my lumbar 3 disc so positioning was going to be a problem. an anyone explain the no DNA info,I get the hemoc, ( old days quaiac ) info Just not that part.

    • The FDA does not force Exact Sciences to provide info on the results of the Cologuard test, even though it runs 5 DNA tests and an occult blood test that the patient can do for himself at home for about $25. A patient with a hemorrhoid or other benign condition that might cause a little bleeding with stool is therefore denied valuable information. This suggests FDA is in bed with Exact Sciences; after all, it is the patient’s blood and DNA, not the company’s.
      For young healthy males, a colonoscopy is a better test, by far. However, the rates of risk rise for older people, females, those who have had abdominal surgery, and other conditions.

Your daily dose of news in health and medicine

Privacy Policy