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.
Related Reading: Colorectal Cancer and Young Adults: What You Need to Know
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.
Read our blog to learn more about when you should start colon cancer screenings.
Types of At-Home Colon Cancer Tests
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 additional screening for DNA cells that are shed from the colon and the rectum during a bowel movement. Cologuard is a commonly used brand for this test. Upon receipt, the lab extracts 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.
Whatever test is used, it should not be used by women who are menstruating—testing while on your period can produce a false positive.
What the Results Mean for You
Blood in the stool does not necessarily mean you have cancer. There are many other conditions, such as IBD, ulcers, hemorrhoids, colon polyps, or anal fissures, that could be contributing to gastrointestinal bleeding. If blood is found, your doctor will likely recommend additional testing to determine the cause of your positive test result.
Additionally, tests such as Cologuard will look for genetic changes that could signal the presence of colorectal cancer. The results will indicate if any mutations are present.
If you receive a negative test, no blood was found in the sample, and no genetic changes were noted.
Should you receive inconclusive — neither positive nor negative — results, it’s possible that there was an issue with your specimen. In cases such as this, your primary care physician might recommend testing 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.”
Visual Tests Used for Colorectal Cancer Screening
While there are advantages to at-home colon cancer tests, they also have some disadvantages. Even though convenient and non-invasive, at-home tests aren’t as accurate as other types of colon cancer screening. Their higher probability of false positives and false negatives means that you’re likely to need follow-up testing anyway. At-home tests can also be difficult to administer for some people. When tests aren’t administered accurately, there’s a good chance you’ll need to schedule an appointment with your PCP for follow-up testing.
If an at-home test isn’t an option for you, there are a couple of other colon cancer tests to consider, which include:
- Standard colonoscopy. Most commonly used, this procedure uses a thin tube with a lens to examine the entire colon. Polyps or other tissues are also often removed for biopsy. Before a colonoscopy, your doctor will provide you with instructions that will help you clear out your colon as much as possible prior to testing. While the colonoscopy prep can take a few days, the test itself usually takes less than an hour. Luckily, improvements have been made to the preparation process, and a new colonoscopy prep tablet may make it easier for patients to prepare.
- Virtual colonoscopy. Also known as computed tomography colonography (CTC), this test takes pictures of the colon through a series of x-rays or tomography, which produce digital images that show abnormalities. This test also requires colon cleansing in preparation. If polyps or other growths are found, a standard colonoscopy will be the next step to remove them. Further testing may also be needed if screening detects possible issues with surrounding organs, such as kidneys, liver, spleen, and pancreas.
- Flexible sigmoidoscopy. In this procedure, a small tube-like instrument with a light and lens is used to look inside the rectum and lower (sigmoid) colon for polyps or other irregularities. Polyps or tissue samples may be removed and checked for signs of cancer. Sigmoidoscopy is less invasive and tends to take less time (about 15 – 20 minutes) than a standard colonoscopy. While it doesn’t generally doesn’t require an anesthetic, your doctor may provide you with a relaxant. Your doctor will tell you what you need to do to prepare.
Annual Screenings for Colon Cancer Can Save Your Life!
The colon cancer doctors at Compass Oncology recommend annual colon and rectal cancer screening for early detection and prevention starting at age 45. While there is some risk of receiving a false positive or having a complication in some of the screenings, the benefits of screening far outweigh the risks. We encourage you to consider all your possible risk factors for colon cancer. Early detection and early treatment of cancer bring much better results. It can save your life.
If abnormal test results determine that colon cancer was detected, the specialists at Compass Oncology are here to provide you with a treatment plan specific to your stage and location of the cancer. We also provide second opinions. Request an appointment at one of our cancer centers located in Portland, Tigard, or Vancouver, WA.