Colon and rectal cancer testing can be uncomfortable to talk about. And preparing for a colonoscopy isn’t a lot of fun. Because of that, many people delay this important screening test. But with the development of at-home stool tests, it’s easier than ever for those at average risk to get started with colorectal cancer screening.
Colonoscopies are the gold standard in colon and rectal cancer screening because the doctor is able to look into the colon for polyps and take tissue samples of anything that may look unusual. However, compared to a colonoscopy, at-home colon cancer tests offer much more convenience. While you can’t solely use at-home tests for colorectal cancer screening throughout your life, you might be able to use this option first.
Watch to see a comparison of at-home colorectal cancer test kits versus a colonoscopy.
When Should You Start Colorectal Cancer Screening?
Colorectal cancer is no longer only affecting older adults. Since the mid-1990s, there’s been a rise in the disease among individuals in their 30s and 40s.
This shift has changed when colorectal cancer screening should begin. According to the American Cancer Society, average-risk individuals should be screened starting at age 45. Earlier or more frequent screening may be recommended for high-risk people with certain pre-existing conditions such as adenomatous polyps (adenomas), inflammatory bowel disease (including ulcerative colitis or Crohn’s disease), diabetes, and genetic syndromes, as well as a family or personal history of colorectal cancer. Some lifestyle factors can also put you at high risk, including lack of exercise, consuming a low-fiber, high-fat diet or a diet high in processed meats and low in fruits and vegetables, being overweight, and smoking.
Colon cancer tests look for occult blood — blood that can’t be seen with the naked eye — in fecal matter or your stool. Therefore, colon cancer tests are called fecal occult blood tests (FOBT). With FOBTs, a stool sample must be submitted to a lab so it can be inspected for the microscopic presence of blood. This type of screening helps doctors diagnose benign (noncancerous) conditions and detect the presence of colorectal cancer.
The US Food and Drug Administration (FDA) has approved a few different stool tests that can be used for colon cancer screening. The collection methods referenced above are typical but may vary according to test kit manufacturers. For best results, following the directions and ensuring kits are used before the expiration date is important.
Fecal Immunochemical Test (FIT or iFOBT)
A more affordable and highly sensitive test, the FIT, involves the use of antibodies that bind to hemoglobin protein — a protein that indicates whether blood is present in the stool. Collecting a stool sample is fairly simple: a fecal sample is scraped with a small probe, inserted into a sampling container, and returned to the lab. Although a change in diet isn’t required before testing for the FIT, certain medications may affect test results. It is best to consult with your healthcare provider about what to avoid or modify before the test.
Guaiac FOBT (gFOBT)
The gFOBT also looks for blood in the stool — specifically, the presence of heme, a component of hemoglobin. Samples from a few different bowel movements are taken with applicator sticks, smeared onto a paper card coated with guaiac, and then sent back off for testing. At the lab, hydrogen peroxide will be added to the card. Cards that turn blue mean that blood is present.
The gFOBT is very sensitive. Therefore, before testing, your doctor may ask you to stop eating foods containing heme in preparation to avoid a false positive. This might include refraining from red meat, poultry, seafood, turnips, horseradish, and citrus fruits and juices. Certain nonsteroidal anti-inflammatory drugs (NSAIDs) and supplements, such as Vitamin C and iron, can also affect test results. Be sure to ask your doctor if there are any adjustments you need to make before you take the test.
Stool DNA Test (FIT-DNA)
This is a test that combines the FIT with