Home Colon Cancer Tests

Adults age 45 or older, the age when screening for average-risk people begins, may be eligible for an at-home screening option. Here are answers to commonly asked questions about at-home tests for colorectal cancer.

Ready to learn more about your personal colorectal cancer risk, and when screening is recommended for you?

Types of colorectal cancer screening tests

There are a few different types of colorectal cancer that can be done at home. These are often referred to as “stool tests.”

FIT-DNA/FIT-fecal DNA/mt-sDNA (for example, Cologuard®)

This test looks for small amounts of blood or DNA markers associated with colorectal cancer. One stool sample is needed, and it can be collected at home and then sent to a lab. This test is repeated every three years, if normal. An abnormal test does not necessarily mean you have cancer, but it requires a follow-up colonoscopy to determine why the test is abnormal.

Fecal immunochemical test

The fecal immunochemical test (FIT) can identify small amounts of blood that are microscopic and difficult for you to see. One stool sample is sufficient, and it can be collected at home. This is a low-cost option, but the test must be repeated every year, if normal. An abnormal test does not necessarily mean you have cancer, but it requires a follow-up colonoscopy to determine why the test is abnormal.

Test similarities

With both the mt-sDNA and FIT, patients collect stool samples at home. A kit is provided with step-by-step instructions. (Follow the instructions for the test you choose; they’re different.)

Get your doctor involved and review the results together. Both tests look for small amounts of blood in the stool sample provided. Both tests also require patients to undergo a follow-up colonoscopy if the result is positive (which means it’s abnormal).

Important: If your doctor advises of a positive finding (meaning your at-home test came back abnormal), you will need to have a follow-up colonoscopy. Do not skip this step. Be sure to schedule your follow-up colonoscopy as soon as possible.

Differences in home tests

The National Institutes of Health describes the differences between the Cologuard and FIT:

“mt-sDNA (Cologuard) detects hemoglobin, along with certain DNA biomarkers. The DNA comes from cells in the lining of the colon and rectum that are shed and collect in stool as it passes through the large intestine and rectum. FIT uses antibodies to detect hemoglobin protein specifically. Dietary restrictions are typically not required for FIT.“

If your at-home test is negative, you will need to perform another Cologuard test in three years. If your FIT is negative, it should be repeated in one year.

Insurance Coverage

For the most patients, the at-home tests are covered by insurance.

If the test result is abnormal and a follow-up colonoscopy is needed, patients with private insurance, Medicare, and most Medicaid patients should not have out of pocket costs. This is a recent change following extensive advocacy from Fight CRC and our partners.

Stool test accuracy

In general, Cologuard will detect 9 out of 10 cancers as a single-time test. FIT will detect 8 out of 10 cancers.

The American College of Surgeons (The ACS) compared colonoscopy vs. mt-sDNA and found cancer detection rates to be equivalent.

Downsides to an at-home test 

Polyp detection rates are drastically different between at-home tests and colonoscopy.

“Colonoscopy is 75%–93% sensitive for finding any type of polyp smaller than 6 mm … FIT-fecal DNA test proved a detection rate for high-grade dysplasia of 62%, which then fell to 42% for detecting any type of polyp.”

ACS

False-positive results may also be higher with a FIT or mt-sDNA compared to a colonoscopy. Additionally, stool tests do not explain what is causing the bleeding if they come back positive.

However, as the ACS noted, an at-home colon cancer test is the best test option if the alternative is not getting colorectal cancer screening done. Several patients prefer at-home tests due to affordability, ease, privacy, and the ability to skip colonoscopy prep.

Who is and isn’t eligible for an at home test

The purpose of at-home colon cancer test is to check for cancer in people who do not show signs or symptoms and who are at the colorectal cancer screening age.

Important: If you have a family history of colorectal cancer or if you have signs and symptoms, a colonoscopy is the best test for you.

Will a colon cancer test from a drug store work?

If you obtain a stool test from a drug store or health fair, it will likely work. However, we highly recommend either obtaining the test from your doctor and/or getting your doctor involved right away. We understand it may be more convenient and cost effective for you to buy and take the test on your own.

Causes of a positive result

These tests work by detecting minuscule (traces that are often unseen by the human eye) amounts of fecal blood. The tests cannot determine why or what may be causing the bleeding, but only that blood is present in your stool sample.

In addition to checking for blood in the stool, an mt-sDNA test looks for abnormal sections of DNA. If it finds either, you may receive a positive test result. But does a positive stool test mean cancer? No, it does not.

However, it’s critical to schedule a follow-up colonoscopy to determine why the stool test was positive.

Ultimately, a positive result does not mean you have colorectal cancer. But please take the results seriously and schedule your follow-up colonoscopy as soon as possible.

Get a home stool test

While you can likely find a test online or at a drug store, we highly recommend talking to a general internist, a primary care doctor, or an OB-GYN doctor to make decisions about what colorectal cancer screening test is best for you. Your doctor will not only help you obtain a reliable test, but follow up and explain your results and your next steps.

Medical Review

University of Colorado Anschutz Medical Campus

Swati G. Patel, MD, MS

Last Reviewed: December 31, 2022