Cologuard is a colon cancer screening test you can do at home. It’s a noninvasive, stool-based test that comes in a kit. You use the kit to collect a stool sample. Then you send the sample to a lab for testing. Your primary care provider can give you a Cologuard test kit or have one mailed to you.
The U.S. Preventive Services Task Force recommends colorectal cancer screening for all adults starting at age 45. After age 75, the task force recommends talking with your health care team to decide if you still need screenings. If you are at high risk for colon cancer, you may need to start screenings before age 45 or have them more often.
Other at-home screening tests for colon cancer include the fecal immunochemical test (FIT) and guaiac-based fecal occult blood test (gFOBT). An additional screening option is getting a colonoscopy.
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How Cologuard Tests Help Diagnose Colon Cancer
Cologuard is a FIT-DNA test, which means it’s two tests in one. (You might also see this written sDNA-FIT.) FIT stands for fecal immunochemical test. This part of the test checks for blood in the stool using antibodies. Polyps or cancer may bleed, but they may not release enough blood for you to notice. It may be only a very small amount that you can’t see. FIT can detect this hidden (occult) blood. More precisely, it can detect the hemoglobin protein in blood.
The DNA part of the test checks for abnormal sections of DNA. This may show up if cancer or polyp cells have come off the lining of your colon or rectum and are in your stool.
If the test is positive (it found signs that might be from colon cancer), you will need a colonoscopy to find out why. If the test doesn’t find any signs of cancer, the usual schedule is to repeat the Cologuard test every one to three years.
Cologuard Tests for Colon Cancer FAQ
Each type of colon cancer screening has advantages and disadvantages. Cologuard may or may not be the best test for you. To decide, it’s a good idea to talk about the options with your primary care provider. Here are some of the things to consider about using Cologuard:
- You can do the test at home. You don’t have to go to a clinic or office. You do have to collect an entire bowel movement and ship it.
- You don’t need to do bowel prep before the test.
- You don’t need to be sedated for the test.
- The test is not invasive. Testing tools are not put in your body.
- Even if the results are negative (no problem detected), you need to repeat the test every one to three years (versus every 10 years for colonoscopy).
- If the test detects a problem, you need to have a follow-up colonoscopy.
- Cologuard alone doesn’t let your physician remove polyps or abnormal tissue to prevent or diagnose colon cancer.
You don’t need to do anything special to prepare for a Cologuard test. You don’t need to change your diet or medicines or do bowel prep (steps to clean out your colon), like for a colonoscopy.
When you’re ready to use your kit, open it up and follow the instructions step by step. The kit contains the supplies you will need. You will collect a full stool (entire bowel movement). The kit has a container for this and a bracket to connect the container to your toilet. After going to the bathroom in the container, you’ll also use a small stick or brush from the kit to take a sample of the stool. You’ll seal this small sample in a tube. Next, you will pour a bottle of preservative into the larger container and seal it. Then label your samples. The kit includes a mailing label so you can send your samples to the lab in the same box it came in. Typically, the kit says to send the sample back the same day or the next day after you collect it.
If you have questions about using your kit, call your primary care provider (or other member of your health care team who arranged the test for you). Your provider will let you know when the results are back.
The U.S. Preventive Services Task Force published updated guidelines on colorectal cancer screening in 2021. The guidelines had this to say about sDNA-FIT tests, like Cologuard:
- sDNA-FIT is more sensitive than regular FIT. In medical tests, sensitivity means how well a test can detect a specific condition in a person who has that condition.
- sDNA-FIT is less specific than regular FIT. In medical tests, specificity means the percentage of people who test negative for a condition among a group of people who do not have the condition. Lower specificity means there are more false positives (more people with a test result that shows a problem even though there is not actually a problem).