What Is the Cologuard Test?

Cologuard is a non-invasive test for colon cancer that you can perform in the comfort of your own home. It checks for evidence of cancer in a small sample of stool (poop) that you mail to a lab.

Cologuard is less accurate than a colonoscopy—the preferred method of screening—and is not a replacement for that test. However, it may be appropriate for people who might otherwise avoid colon cancer screening. Cologuard is also less costly than a colonoscopy and may be fully covered by insurance.

This article describes the Cologuard test, how it works, how to interpret results, how much it costs, and the pros and cons of the Cologuard test.

What Is the Cologuard Test? 

Cologuard is one of six approved methods for colon cancer screening in the United States, including one of three stool-based tests. It is used to detect colon cancer, also known as colorectal cancer, which is the third most common cause of cancer deaths in the United States.

Fortunately, with routine screening starting from age 45, the risk of colon cancer and colon cancer deaths can be greatly reduced.

Cologuard has gained popularity since its approval in 2014. The FDA approval was granted in part to improve rates of colon cancer screening, which prior to Cologuard’s release stood at 65%. By 2019, the rate increased to nearly 70%, with Cologuard accounting for 14% of all screening methods.

The Cologuard test is able to detect blood in a sample of stool—a key sign of colon cancer—as well as 10 different gene mutations associated with colon cancer (including NDRG4, BMP3, and KRAS mutations).

Cologuard is able to do so because the lining of the colon (large intestine) is shed several times a day, along with cells from precancerous polyps and cancerous tumors. These cells end up in the stool along with traces of blood from bleeding tumors.

While Cologuard is not the preferred method for colon cancer screening, it remains a highly important and accurate tool for detecting cancer in people at average risk.

Who Should Use the Cologuard Test? 

Despite its convenience and ease of use, Cologuard may not detect early-stage precancerous growths. Because of this, the Food and Drug Administration (FDA) has approved its use for adults 45 and over who are at average risk of colon cancer. A person at average risk has about a 4% chance of developing colon cancer.

Cologuard should not be used in people at high risk for colon cancer; colonoscopy remains the preferred choice.

The vast majority of colon cancers are sporadic, meaning the genetic causes of cancer happen by chance after a person is born. But 5% of colon cancers are inherited, meaning the cancer-related genetic mutations are passed from one generation to the next.

Having genetic mutations for cancer doesn’t mean you will get cancer but it does greatly increase your risk.

Choosing Cologuard

Cologuard is approved for use in people at average risk of colon cancer. The U.S. Preventive Services Task Force (USPSTF) defines this as adults 45 and over who do not have:

• A personal or family history of colon polyps or colon cancer
• A diagnosed genetic disorder associated with colon polyps, such as Lynch syndrome or familial adenomatous polyposis (FAP)
• Inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis

Choosing Colonoscopy 

For some people, a colonoscopy is a far better option than Cologuard. People who have a personal or family history of colon cancer or colon polyps, a known genetic disorder linked to colon cancer, or inflammatory bowel disease are at high risk and should get a colonoscopy.

A colonoscopy might also be recommended for people who have signs and symptoms of colon cancer, including:

• A change in bowel habits (meaning a change in the frequency, consistency, or color of stools or the ability to control bowel movements)
• Blood in or on your stool
• Diarrhea or constipation (including fluctuating bouts of diarrhea or constipation)
• Feeling that your bowel isn't empty even after a bowel movement
• Abdominal cramps, pain, or aches that won't go away
• Unexplained weight loss

How Does the Cologuard Test Work?

You will need a prescription from your healthcare provider to get a Cologuard kit. The kit will be shipped directly to your home and includes a larger collection container, a smaller specimen tube, a bottle of preserving liquid, labels, and instructions.

If you have any questions about how to use the kit, you can speak with your healthcare provider or call Cologuard Customer Care at 1-844-870-8870.

There are a few things you should know before performing the test:

• You should complete the test before the expiration date on the kit.
• Try not to get urine on the sample. Empty your bladder before having a bowel movement.
• Collect the sample when you know you can return it within one day.
  

To collect a stool sample: 

1. Remove the large collection container and remove the lid.
2. Place the container on the toilet bracket according to the instructions.
3. Sit on the toilet and have a bowel movement into the container.
4. Remove the container and place it on a counter.
5. Next, take the enclosed sample tube and unscrew the lid. The lid has a long, stem-like probe with grooves.
6. Scrape the surface of the stool with the probe until it covers the grooves.
7. Put the probe back into the sample tube and screw the lid tightly.
8. Next, open the bottle of the preservative and pour the entire contents into the collection container.
9. Replace the lid of the collection container, screwing it tightly.
10. Place both the collection container and sample tube into the return shipping box.
11. Follow the instructions for packing and shipping the sample.
12. Drop the box off at a UPS location, or call 844-870-8870 and ask the manufacturer to schedule a UPS pickup for you.

To see how a sample is collected, go to the Cologuard website for a step-by-step video guide.

Interpreting Cologuard Test Results

After the lab gets your sample, they will evaluate it and send the results directly to your healthcare provider within two weeks. Test results will either be negative or positive.

• A negative test means that no signs of blood or cancer-associated gene mutation were found in the sample.
• A positive test means that Cologuard detected blood and gene mutations suggestive of cancer, indicating the need for further investigation with a colonoscopy.

A positive result does not mean you have cancer. A colonoscopy is needed to confirm a positive result because it could be a false-positive result (meaning that you don’t have cancer even if the test suggests otherwise). False positive results may be due to the limitations of the test or because there is another cause of rectal bleeding.

It is also possible to get a false-negative result, (meaning that you have cancer even if the test suggests otherwise). This may occur if the test is not performed properly.

How Much Does it Cost?

On paper, there is an enormous difference in the cost of Cologuard versus the cost of colonoscopy. In the United States, the Cologuard kit is roughly $500, while the average cost of a colonoscopy is around $2,125.

Even so, your actual out-of-pocket costs (meaning the amount not covered by insurance) may be the same. This is because both screening tests fall under the list of Essential Health Benefits (EHBs) prescribed by the Affordable Care Act (ACA).

EHBs are specific tests and procedures that under provisions of the ACA must be covered by health insurers in the United States, including Medicare, Medicaid, and private insurance.

This doesn’t mean that there will be no out-of-pocket expenses for provider visits and other care-related costs. But studies have shown that the average out-of-pocket costs for a colonoscopy are around $79.

Cologuard Pros and Cons

There are pros and cons to both Cologuard and colonoscopy.

Cologuard Test vs Colonoscopy

The main difference is that Cologuard is non-invasive. Cologuard involves collecting a stool sample in the privacy of your home and mailing it to a lab. There is no sedation or anesthesia involved. With that said, if a positive result is returned, a colonoscopy would be needed.

By contrast, a colonoscopy is an outpatient procedure in which you need to undergo bowel preparation a day before to remove all traces of stool. On the day of the procedure, you will be sedated, and the healthcare provider will examine your colon and remove any polyps they find. The removal of polyps is a preventive measure to reduce your risk of colon cancer.

Test Accuracy

Another difference is in the accuracy of the two tests. Of the two, colonoscopy is more accurate and needs to be performed less often as a result.

According to the USPSTF:

• Colonoscopy is recommended every 10 years starting from the age of 45.
• Cologuard is recommended every one to three years starting from the age of 45.
  

Accuracy of Cologuard

As an indirect method of testing, Cologuard doesn’t detect precancerous polyps well and is best suited for detecting larger, more advanced cancerous tumors.

In terms of specificity (meaning the ability to correctly identify people without cancer), the Cologuard test is up to 87% accurate in detecting colon cancer (not precancerous polyps).

In terms of sensitivity (meaning the ability to correctly identify people with cancer), Cologuard is 92% accurate.

Accuracy of Colonoscopy

Because colonoscopy directly visualizes the colon, it can detect both cancerous tumors and precancerous polyps.

In terms of specificity, colonoscopy is up to 95% accurate when performed every 10 years. In terms of sensitivity, the test is up to 95% accurate.

Summary

Cologuard is a noninvasive screening tool for colon cancer and precancerous polyps. It looks for cancer-related genetic mutations and evidence of blood in the stool. The test is collected in the privacy of your own home. Once you have a sample ready, you send it to the lab for testing.

Cologuard has gained popularity because it’s less invasive and more convenient than going in for a diagnostic colonoscopy. It also comes with drawbacks, including concerns about accuracy and the need for more frequent testing.

A Word From Verywell

Both Cologuard and colonoscopy come with pros and cons. When it comes to the best option for you, it is important to understand the benefits and drawbacks of each screening method.

Reach out to your healthcare provider about any concerns you may have about Cologuard or colonoscopy, as well as your personal risks for colon cancer.