March 14, 2023
What to Know About At-Home Colon Cancer Tests
Most people don’t get too excited about their next colonoscopy with all of the colon prep that’s needed. It can be very easy to put off. But did you know you may be eligible for colorectal cancer screening using a different method?
While colonoscopies are the gold standard in colon and rectal cancer screening, people who are considered at average risk for this disease may prefer an alternative: at-home colon cancer screening.
At-home colon cancer tests are certainly more convenient than a colonoscopy procedure. Let’s take a look at how they’re used.
Types of At-Home Colon Cancer Tests
The type of screening that checks for the presence of blood in a stool sample is called a fecal occult blood test, which is also referred to as an FOBT. Because occult blood isn’t visual to the naked eye, a stool sample must be submitted to a lab so it can be inspected for the microscopic presence of blood. Screening in this manner can help doctors diagnose benign (noncancerous) conditions, such as hemorrhoids, and detect potential colorectal cancer.
There are a few different stool tests approved by the US Food and Drug Administration that can be used for colon cancer screening. For all of them, you should have the kits ordered by your doctor. You’ll then be contacted directly by the lab company to have the kit sent to you.
Be sure you follow all of the instructions to get accurate results!
Fecal Immunochemical Test (FIT or iFOBT)
This test is more widely used because of its cost and increased sensitivity in detecting blood in the stool. The testing process involves the use of antibodies that bind to hemoglobin protein, which indicates whether blood is present in the stool. Stool sample collection is relatively straightforward: a fecal sample is scraped with a small probe, inserted into a sampling container, and returned to the lab. Changes in diet are not required before testing for the FIT; however, 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. In this test, you use applicator sticks to collect a few samples from different bowel movements. The samples are smeared onto a paper card coated with guaiac and then sent back off for testing, where hydrogen peroxide will be added to the card. Cards that turn blue mean that blood is present.
Because this test is very sensitive, your doctor may ask you to stop eating foods that contain heme in preparation for testing 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 skew results. It’s a good idea to talk with your doctor about what adjustments you need to make prior to testing.
Stool DNA Test (FIT-DNA)
This combo test detects blood in the stool and screens DNA cells that are shed from the colon and the rectum during a bowel movement. Once the sample is received, the lab can extract DNA from the stool to identify whether or not mutated or abnormal genes are present. This test collects a full stool sample and does not require dietary changes. Cologuard is an example of this type of test.
Regardless of which test is chosen, women should avoid administering the test while on their period. Doing so can produce a false positive.
Stool Test Results: What They Mean for You
You might be wondering if the presence of blood in the stool means you have cancer. The answer is not necessarily.
There are many other conditions, such as IBD, ulcers, hemorrhoids, polyps, or anal fissures, that could be contributing to gastrointestinal bleeding. If blood is detected or genetic changes are found in the stool that indicates cancer might be present, there will be more tests run, including a colonoscopy.
If you receive a negative test, no blood was found in the sample.
In some cases, individuals might receive an inconclusive test result, which means that there might have been an issue with your specimen. If this happens to you, your primary care physician might request that you take the test again.
Your doctor will be able to discuss the risks of receiving either a false-positive or false-negative result. Despite the risk, the National Cancer Institute points to probable benefits, “Studies show that some screening tests for colorectal cancer help find cancer at an early stage and may decrease the number of deaths from the disease.”
What About Black Stools? Are They a Sign of Cancer?
There are several factors that could contribute to black, tarry bowel movements. Sometimes, this change in stool color is harmless — simply the result of certain foods or medications that can cause stool to appear darker than usual. Once these items are no longer being ingested, however, the discoloration will stop.
In other cases, black stool could be the result of something more serious, such as ulcers, esophageal tears, swollen veins, or cancer. If you notice black, tarry stools for more than a few days, it’s a good idea to contact your doctor to discuss possible causes and tests that may need to be run.
Other Available Tests to Screen for Colon Cancer
As convenient and non-invasive at-home colon cancer tests can be, it’s important to understand that they have some disadvantages you should be aware of. For one, at-home testing isn’t as accurate as other types of colon cancer screening. Their higher probability of false positives and false negatives means that you’re more likely to need follow-up testing than if you had a colonoscopy. At-home tests can also be difficult to administer for some people. When tests aren’t administered accurately, this can also result in needing to see your doctor for follow-up testing.
If an at-home test isn’t an option for you, there are a couple of other colon cancer tests that can be used, with a colonoscopy being the most common.
Average-Risk vs. High-Risk Colorectal Cancer Patients Screening Recommendations
The American Cancer Society recommends colorectal cancer screening start at age 45 for people with an average risk of colorectal cancer and no symptoms. Individuals with certain pre-existing conditions, such as ulcerative colitis or genetic syndromes, are considered high-risk and may need to be screened earlier or more often. When should you start colon and rectal cancer screening?
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Annual Screenings Can Help Detect Colon Cancer Early
The cancer specialists at Affiliated Oncologists recommend annual colon and rectal cancer screening for early detection and prevention starting by age 45. Talk to your primary care doctor by age 40 to discuss the right timing for you and which tests should be used.
If abnormal test results determine that colon cancer is present, the cancer doctors at Affiliated Oncologists are here to help by creating a personalized colorectal cancer treatment plan. We also offer second opinions as you consider your next steps.