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How Accurate Are At-home Colon Cancer Screening Tests?

Table of Contents

    Background

    Colorectal cancer is one of the most treatable forms of cancer when it is caught in the earliest stages. Thus, physicians and medical professionals encourage adults over the age of 50 to be screened for colorectal cancer before it has spread to outer lying tissues. Recently, the U.S. Preventive Services Task Force and the American Cancer Society have lowered the recommended age for colorectal cancer screening to age 45. This means that millions of people need to screen for colon cancer due to new recommendations. 

    Many of these millions avoid the screening because they do not want to undergo a colonoscopy with its intensive bowel preparation and the invasive nature of the procedure. For this reason, some physicians will recommend an at-home cancer screening to those that refuse to get a colonoscopy because, in their eyes,  the best screening test for cancer is the one that gets done.  

    Many of these millions avoid the screening because they do not want to undergo a colonoscopy with its intensive bowel preparation and the invasive nature of the procedure. For this reason, some physicians will recommend an at-home cancer screening to those that refuse to get a colonoscopy because, in their eyes,  the best screening test for cancer is the one that gets done.  

    At home colon cancer screenings are a feasible alternative to a colonoscopy to detect bleeding polyps and cancerous cells.

    Efficacy Rates by At-Home Test Provider

    At-home colorectal cancer screening tests generally do not require you to limit your diet, stop taking medications, nor ask you to cleanse your bowels before the test. The tests typically involve the patient taking a small sample of their stools and sending the sample to a lab to analyze for the presence of blood or cancerous cells. There are currently three types of stool tests that are approved for colorectal cancer screening in the United States. These include:

    Fecal immunochemical test (FIT).  This test uses antibodies that specifically react with a blood protein in the stool. Physicians typically order the test to be repeated annually. 

    Fecal occult blood test (FOBT). Conducted yearly, the FOBTuses a chemical to detect microscopic amounts of blood in the stool. 

    Multitarget Stool DNA test (also known as FIT-DNA test). The most current stool test combines the FIT test with a test that can detect abnormally mutated DNA in the stool. Unlike the FIT and FOBT, the multi target stool DNA test can be repeated every three years if no abnormalities are found. 

    Each type of test has its own unique rating of accuracy, including sensitivity and specificity ratings. 

    Sensitivity: Indicates the likelihood that the test will detect if a condition or disease is present in a patient. A test with a high sensitivity is less likely to give a patient a false negative result. 

    Specificity: Indicates the likelihood that the test will rule out if a condition or disease is present. A test with a high specificity will give a low number of false positive results.

    These two factors help to describe how valid or accurate a test is. The following list describes the sensitivity and specificity of major at home colon cancer providers. 

    FIT Providers

    InSure® ONE

    • Sensitivity 26% 
    • Specificity 97%

    Second Generation FIT® Colon Cancer Test

    • Sensitivity 98%
    • Specificity 96% 

    LetsGetChecked® Colon Cancer Screening Test

    • Sensitivity 79%
    • Specificity 94% 

    Pixel by LabCorp® Colorectal Cancer At-Home Test

    • Sensitivity 74%
    • Specificity 96% 

    FOBT Providers

    EZ Detect Stool Blood Test

    • Sensitivity 41%
    • Specificity 97%

    Hemmocult ( includes Hemoccult® II SENSA)

    • Sensitivity 74%
    • Specificity 98.6%

    Multitarget Stool DNA Test Provider

    Cologuard®

    • Sensitivity 88%
    • Specificity 92%

    What Each Test Entails

    Everlywell FIT® Colon Cancer Screening Test

    Customers who purchase Everlywell’s test kits collect their samples at home and return the samples to a partner laboratory that is CLIA (Clinical Laboratory Improvement Amendments) certified. Once the lab tests the samples for the presence of hidden blood, the results are sent digitally to the customer. The results usually arrive within five days from the day the sample was received by the partner lab. The company offers their customers the opportunity to consult with a physician via video or phone if they receive a positive test. 

    Cost

    One kit: $49 

    InSure® ONE™

    Insure ONE is a fecal immunochemical test (FIT) used to detect blood in the stool caused by colorectal cancer, polyps, or large adenomas.The Insure ONE FIT test kit is the only test on the market that uses toilet water collected after a single bowel movement. This means that you simply need to brush the stool sample in your toilet with the long brush provided and brush the toilet water on the test card. There are no dietary or medication restrictions that you need to follow before taking the test. The test is provided by a prescription from your physician and you can submit the test to your physician or laboratory for analysis. 

    Second Generation FIT® Colon Cancer Test

    The Second Generation FIT test has a high degree of sensitivity for detecting polyps and colorectal cancer.Performance data for Pinnacle Biolabs’ FIT attest to its accuracy in colon cancer detection:

    • 98% sensitivity for detecting microscopic amounts of blood (above 50ng/mL)
    • 96% specificity for ruling out patients with no blood in their stools’
    • 63% detection rate in finding precancerous adenomas (abnormal tissue growths)
    • Patients do not need to alter their diet or stop taking medications

    People who purchase the Second Generation FIT test kit are able to collect the stool sample at home and receive instant results. Customers report finding the instructions easy to follow and are pleased that the test is non-invasive and does not require them to avoid any foods or medications.

    Cost

    One kit: $25.00

    EZ Detect Stool Blood Test

    The EZ Detect blood stool test is sold in most major drugstores in the United States. You can also order the test online. The FDA has cleared the blood stool test to be purchased by individuals over the counter (without a prescription). The test is simple to take and involves the following steps:

    1. You do not need to restrict your diet or stop taking medications. 
    2. Have a normal bowel movement. 
    3. Drop the test tissue into the toilet bowl. 
    4. Observe the tissue for a color change for two minutes. 
    5. The tissue changing to a blue-green color indicates an abnormal amount of blood is present in the stool. 

    Cost

    One kit: $8.00 

    LetsGetChecked® Colon Cancer Screening Test

    The colon cancer screen test is similar to other blood stool tests.The tests are affordable, samples are taken at home, and results are returned within 5 days of the lab receiving the stool sample. If you have any questions you can chat with an online consultant before buying the test kit.  Free phone consultations with a registered nurse is available for people who test positive for a medical condition using one of LetsGetChecked tests.

    Cost

    One kit: $69

    Pixel by LabCorp™ Colorectal Cancer At-Home Test

    The stool test requires that a person collects a sample from home and mail the sample to a lab for analysis. There are no restrictions on diet nor medications before taking the test. If you choose to purchase the Pixel FIT test, you have access to PWNHealth, an independent physician partner group that offers consultations if you get a positive result. Your results are provided digitally at the Pixel website and you can download the results and discuss them with your physician.

    Cost

    One kit: $99 

    Hemoccult

    This fecal occult blood test detects blood in stool samples to help identify bleeding polyps or adenomas. People who use Hemoccult tests do not have to restrict their diets or medications. The test itself is stable for up to two weeks after taking the test and has a high clinical sensitivity. There are several types of Hemoccult tests available on the market, including Hemoccult II, Hemoccult ICT, and Hemoccult Sensa. The test is typically covered by Medicare, Medicaid, and by most health insurance providers. If you are paying out-of-pocket, ask your physician how much it costs as it is available by prescription only. 

    Cologuard Screening Test 

    This colorectal screening test is a combination of two tests, the fecal immunochemical test and a DNA screening for abnormal cancer cells. Lab pathologists test stool samples for increased levels of mutated or altered DNA biomarkers that are found in shedded colon cells. These biomarkers indicate the presence of colorectal cancer or precancerous tumors known as adenomas. Samples are also tested for the presence of the globin protein found in blood using the antibody test, fecal immunochemical test (FIT).  Available by prescription only.

    Cost

    One kit:$599 

    How To Make Your Test More Accurate

    The reason many people choose an at home screening test for colorectal cancer is because the test generally does not require an intensive limited diet regimen and cessation of taking medications. However, each test is different and it is important you follow the directions given to you in the test kit or those given to you by your doctor to make sure the test is performed correctly and will give you accurate results. 

    Many people can receive a false-positive result because they have blood in their stools from hemorrhoids or a bleeding ulcer in their upper intestinal tract. Pain relievers such as aspirin and ibuprofen are hard on the digestive tract and can also cause bleeding resulting in a false-positive result. 

    If you choose a FIT or Cologuard test to screen for colon cancer at home, you typically do not have to restrict your diet nor stop medications before you take your test. However, the fecal occult blood test, or FOBT, is a chemically sensitive test and does require you to restrict your diet a couple days before the test. This is because certain foods and medications can trigger false-positive or false-negative results. 

    The fecal occult blood test (FOBT) carries the most restrictions due to the chemical reaction the test uses to detect blood in the stool. Many foods can interfere with this reaction and are listed below.  

    Foods or medications that may cause FOBT results to come back false-positive

    Drugs and substances

    • Aspirin
    • Nonsteroidal anti inflammatory drugs (NSAIDs)
    • Boric acid
    • Bromides
    • Colchicine
    • Iodine

    Foods and supplements

    • Red meat
    • Beets
    • Carrots
    • Cauliflower
    • Mushrooms
    • Broccoli
    • Radishes
    • Turnips
    • Horseradish
    • Cantaloupe
    • Iron supplement

    Foods or medications that may cause FOBT results to come back false-negative

    • Vitamin C – This powerful antioxidant interferes with the chemical reaction that detects the presence of blood through a color change
    • Iron supplement that contains at least 250mg of vitamin C

    Besides the FOBT’s standard restrictions, people who are using all three types are typically asked to take the following precautions:

    • Avoid taking NSAIDs (nonsteroidal anti-inflammatories) and aspirin the week before your at home screening test
    • Do not take the screening test if you are on your period
    • Do not take the screening  test if you have actively bleeding hemorrhoids 

    Many people can receive a false-positive result because they have blood in their stools from hemorrhoids or a bleeding ulcer in their upper intestinal tract. Women may receive a false-positive result if they are on their menstrual cycle while taking the at home test. Pain relievers such as aspirin and ibuprofen are hard on the digestive tract and can cause bleeding resulting in a false-positive result. 

    In order to avoid these inaccurate results, check with your doctor if you have hemorrhoids or tend to get ulcers before you follow through with the at home stool test. 

    References

    Lohsiriwat, V. (2014). Accuracy of self-checked fecal occult blood testing for colorectal cancer in Thai patients. Asian Pacific Journal of Cancer Prevention, 15(18), 7981-7984. Retrieved from APOCP: http://journal.waocp.org/?sid=Entrez:PubMed&id=pmid:25292099&key=2014.15.18.7981

    Rabeneck, L., et., al. (2012, March 01). Fecal immunochemical tests compared with guaiac fecal occult blood tests for population-based colorectal cancer screening. Canadian Journal of Gastroenterology, 26(3), 131-147. Retrieved from Europe PMC:http://europepmc.org/article/PMC/3299236

    Ramdzan, A. R., et., al. (2019, May 19). Diagnostic accuracy of FOBT and colorectal cancer genetic testing: A systematic review & meta-analysis. Annals of Global Health, 70. Retrieved from Annals of Global Health: https://annalsofglobalhealth.org/articles/10.5334/aogh.2466/

    Watson, R. (2020, August 03). Cologuard for cancer screening: What you need to know. Retrieved from Healthline: https://www.healthline.com/health/cologuard

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