The United States will see more than 150,000 new colon cancer cases in 2023. This makes it one of the most common cancers out there. And so, the importance of getting tested for colon cancer is simply a no-brainer.
Fortunately, for those who want to get tested, some options allow them to get tested without having to go to a hospital or undergo a colonoscopy.
Of course, these home tests are not the gold standard for diagnosing colon cancer. You can learn why in our post on Cologuard vs Colonoscopy.
But since many patients ask us about home colon cancer tests, here’s a comprehensive guide to colorectal cancer screening at home.
What are the types of at-home colon cancer tests?
There are three main types of at-home colorectal cancer screening tests. These include the fecal occult blood test, fecal immunochemical test, and fecal DNA testing. Let’s discuss how they detect colorectal cancer, their accuracies, and the pros and cons of each test.
Fecal occult blood test (FOBT)
A FOBT looks for traces of blood in the stool. These trace amounts of blood cannot be seen with the naked eye, hence the term “occult blood”.
The test works by placing a stool sample on a FOBT test card. The card contains guaiac (a plant-based chemical) that reacts with blood in the stool. This changes the card’s color, which is then sent to a physician’s office or a laboratory for interpretation.
It is important to highlight that the FOBT detects occult blood, which does not always mean colon cancer. Other conditions can cause blood in the stool, such as hemorrhoids, inflammatory bowel disease (IBD), and stomach ulcers. This is why a positive FOBT means additional investigations are required to diagnose colon cancer.
According to the Centers for Disease Control and Prevention (CDC), a FOBT should be performed every year to detect cancer.
The FOBT has a 71% sensitivity for detecting colon cancer. This means out of 100 colon cancer patients who take this test, only 71 will get a positive result.
The FOBT has several benefits, including:
- Affordable: This is an inexpensive test when compared to the cost of booking doctor appointments and traveling to a healthcare center.
- Convenient: As with all at-home screening tests, FOBT is a more convenient option versus traditional colon cancer screening.
Despite its convenient use, the FOBT has drawbacks that must be considered.
- Can’t confirm colon cancer: Because the FOBT looks for blood in the stool, it can’t differentiate between colon cancer and other causes of occult blood. Examples include hemorrhoids, fissures, a benign polyp, and IBD. This means that the FOBT will falsely be positive in many people who do not have colon cancer.
- Diet may alter results: Foods like red meat, turnips, and radishes need to be avoided before a person takes the FOBT. Otherwise, it may come out falsely positive.
- Medicines may alter results: Certain medicines, such as aspirin, ibuprofen, and naproxen, can also make an FOBT false positive.
Fecal immunochemical test (FIT)
Like an FOBT, the FIT — also called immunochemical FOBT (iFOBT) — detects blood in the stool. But unlike an FOBT, it uses antibodies against blood to detect it.
To perform a FIT, place a sample collection bag under the toilet seat. After a bowel movement, use the applicator by poking it into the stool at several sites. Next, put the applicator into the collection tube, label it, and mail it to a laboratory.
According to the CDC, FIT should be performed every year.
FIT has a higher sensitivity than FOBT. It can detect up to 93% of people who have colon cancer.
Pros of FIT include:
- Inexpensive: Just like the FOBT, FIT is inexpensive. The cost can vary from $10 to $90, depending on the company, but is usually covered by insurance.
- More sensitive: Compared to FOBT, FIT is more sensitive for diagnosing colon cancer.
- Unaffected by diet/medications: Unlike the FOBT, there are no restrictions on diet or medicine before taking FIT.
There are not many cons of the FIT. But it’s not 100% accurate. This means a positive result cannot diagnose colon cancer and will have to be followed by a colonoscopy with a biopsy.
Fecal DNA testing
IT IS VITALLY IMPORTANT TO UNDERSTAND THAT FECAL DNA TESTING “CAN, (ACCORDING TO THE COMPANY LITERATURE) FIND COLON CANCER IN ITS EARLIEST STAGES”
TRADITIONAL SCREENING MEASURES, SUCH AS COLONOSCOPY, CAN FIND PRECANCEROUS POLYPS BEFORE THEY BECOME CANCER. ALTHOUGH AN AT-HOME TEST SUCH AS FECAL DNA TESTING MAY SEEM QUICK, EASY, AND INEXPENSIVE, DO NOT WAIT UNTIL YOU ALREADY HAVE CANCER. DO NOT SUBSTITUTE THIS TEST FOR A TRADITIONAL SCREENING TECHNIQUE.
Also called a stool DNA test, fecal DNA testing looks for abnormal DNA in the stool. Because colon cancer arises due to mutations in the DNA (which leads to abnormal DNA), fecal DNA testing is another way to detect cancerous polyps and colon cancer.
The test works by collecting a stool sample in a container and a tube that comes with the kit. Next, a preserving liquid is poured into the sample container. The lids of the sample container and the tube should then be sealed tightly. Next, label the containers and mail them to the laboratory within 24 hours.
According to the CDC, fecal DNA testing should be performed every three years.
Fecal DNA testing will be positive in 89% of people who have colon cancer.
Pros of fecal DNA testing include:
- More sensitive: Fecal DNA testing is more sensitive to colon cancer than FOBT.
- Convenient: Similar to other home-based tests, fecal DNA testing avoids the hassle of traveling to a clinic.
- Unaffected by diet/medications: Unlike the FOBT, fecal DNA testing requires no diet or medication restrictions.
Cons of fecal DNA testing include:
- Not entirely accurate: Despite a better sensitivity than FOBT, fecal DNA testing is still not 100% accurate. This means those who test positive on this test must undergo a colonoscopy.
- Expensive: Fecal DNA testing is more expensive than other tests. It can cost upwards of $350 for those without insurance.
Cologuard is a stool testing kit by Exact Sciences Corp that combines FOBT and fecal DNA testing into one kit.
Who should go for at-home colon cancer testing?
The CDC recommends that colonoscopy screenings for colon cancer should begin at the age of 45 years and continue up to the age of 75 years.
This recommendation is for regular people with an average risk of colon cancer. For those with a family history of colon cancer or a genetic disease that makes it more likely, screening should begin earlier. Therefore, anyone who qualifies for screening can take colon cancer screening tests at home.
Deciding between at-home testing and traditional screening (via sigmoidoscopy or colonoscopy) depends on three important factors:
- Presence of symptoms: If a person has no signs of colon cancer, they can go for at-home testing. For those with cancer symptoms — such as blood in stools, weight loss, and altered bowel habits, traditional screening may be more suitable.
- Physician’s decision: In some cases, your physician may decide to do a sigmoidoscopy or colonoscopy right away. This is generally the case when a person has noticeable symptoms of colon cancer, a strong family history of the disease, or a genetic disease that makes the condition more likely.
- Preference: Ultimately, the choice between at-home testing and traditional screening lies in your hands. Affordability, convenience, and the accuracy of a screening test all play a role in this decision.
What’s the next step after a positive home colon cancer screening test?
If you took a home colorectal cancer screening test and have a positive test result, the next step is to undergo additional testing. As discussed earlier, no home screening test can detect colon cancer with 100% accuracy.
The only way to definitively diagnose the disease is via a colonoscopy with biopsy, so make sure to see a doctor if you’ve tested positive on a home screening test.
What does a negative at-home colon cancer screening test mean?
If you have a negative at-home screening test, it means that you have a very low chance of having colon cancer.
People between 45 and 75 years who test negative on an at-home test should follow the screening criteria recommended by the CDC. The at-home tests should be repeated as follows:
- FOBT: After one year
- FIT: After one year
- Fecal DNA test: After three years
It’s also a good idea to discuss the test results with your physician and see what they say.
Are at-home screening tests the best way to screen for colon cancer?
No, at-home screening tests are not the best way to screen for colon cancer. While they may be convenient and affordable, they are not 100% sensitive and may fail at picking up cancer.
This is why the gold-standard way of screening for colon cancer is a colonoscopy, where a doctor will insert a flexible tube with a camera into the gut. This allows them to look for colon cancer directly.
Can home screening tests confirm colon cancer?
No, at-home screening tests cannot confirm colon cancer. The only way to confirm colon cancer (or any other cancer, for that matter) is to take a tissue sample and look for cancer cells under a microscope. For colon cancer, this is done during a colonoscopy, which allows the doctor to take a small piece of the gut out and send it to the lab for analysis.
Colon cancer testing at home summarized
Colon cancer rates are on the rise, and both the National Cancer Institute and the American Cancer Society highlight its importance. Luckily, there are easy-to-use test kits available for detecting it at home.
These kits, like the FOBT and FIT test, detect blood in stool samples. They come with instructions on how to collect stool samples, and some might ask you to avoid certain foods or medications prior to testing.
But while these home tests are handy, they can’t show everything. For a complete look inside, a more detailed test, like a virtual colonoscopy, is a better choice.
In addition, these stool tests can sometimes give wrong results, either saying you have colon cancer when you don’t (false positive result) or missing it (false negative result). This is important to keep in mind when interpreting them.
Also, if your personal or family history includes conditions like ulcerative colitis or Crohn’s disease, you might have a higher risk of colon cancer. So, it’s a good idea to start screening earlier than the standard 45 years of age for regular people. If your home test shows a problem, you’ll need a follow-up colonoscopy for a definitive diagnosis.
So, if you’re worried about colon health or have blood in your stool, get a test kit online or talk to your doctor today. Make sure to discuss any out-of-pocket costs or needed follow-up testing with them.