At-Home Colon Cancer Test: How Does It Work?

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In the U.S., colon cancer (or colorectal cancer) causes 50,000 deaths per year, making it the country’s third most common cancer. It usually begins as small clumps of non-cancerous cells, called polyps, in the large intestine, the final part of the digestive tract. Polyps produce almost no symptoms but, over time, can develop into cancers. Screening for polyps allows them to be removed before they turn into cancer. Doctors recommend regular screening. There’s a number of screening options available, including colonoscopy, colonography, and flexible sigmoidoscopy. An at-home screening option is a stool test. 

What Is a Stool Test?

A stool test is a non-invasive test that can be conducted at home by collecting a sample of your stool after having a bowel movement. Polyp and cancer cells have abnormal DNA. The body continuously sheds these cells and they are found in small quantities in stools. The stool test identifies changes to DNA in the cells found in a stool sample. The test also identifies small quantities of hidden blood in the stool, which may be a sign that cancer is present.

How Does an At-Home Stool Test Work?

The stool test kit contains instructions for how to conduct the test. The kit consists of a container to attach to the toilet and a preservation solution to add to the stool sample. Once the stool sample is collected it can be taken to the doctor or mailed to a laboratory. 

Research has found that at-home stool DNA tests effectively detect precancerous polyps and colon cancer. A positive result will usually require further examination. However, a negative result is not a guarantee that you do not have colon cancer. 


  • The test is non-invasive.
  • It is safe and poses no risk.
  • It can be conducted in the privacy of your own home.
  • You can eat and drink and take medication as normal before the test.
  • Bowel preparation to clean out or empty your colon is not required.


  • Unlike other forms of colon cancer screening, a stool test must be conducted every year.
  • If the test results are unusual, then you may have to have further tests anyway.
  • No screening test is 100% accurate, and there is a chance that cancer could be missed.

Should I Screen for Colon Cancer?

According to U.S. health guidelines, screening for colon cancer should begin at around 50 years of age, and it is recommended that those aged between 45 and 75 should be screened regularly. However, those at higher risk may need to screen earlier and should seek advice from their doctor. These include:

  • African-Americans, who have a 20% higher likelihood of developing colorectal cancer compared to other groups
  • People with a family history of colon cancer, inflammatory intestinal conditions (such as colitis or Crohn’s disease) or certain inherited syndromes that increase the risk of colon cancer

Current evidence suggests that the net benefit of colon cancer screening for older adults aged 76 to 85 years is small. People in this age group should discuss their individual need for screening with their doctor, who can make a recommendation based on the individual’s overall health, screening history, and preferences.

Which Colon Cancer Screening Test Is Best for Me? 

Your doctor can advise you on which screening test is best for you. This advice will depend on a number of factors, including your colon cancer risk, if you have previously had unusual or positive screening results, and your personal preference. If test results are normal, a colonoscopy only needs to be conducted once every few years, while an at-home stool test needs to be conducted once a year. Remember, as with all medical conditions and concerns, always consult your doctor for advice. 

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