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Can You Test Yourself For Colon Cancer?

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    Colorectal cancer is the third leading cause of death from cancer for women and men in the United States. Screening for colorectal cancer in order to detect the cancer before it spreads has made a significant impact in the fight against colon cancer. However, the rate of screening in the United States remains low at under 60% despite the benefits. 

    Screening for colorectal cancer in order to detect the cancer before it spreads has made a significant impact in the fight against colon cancer. However, the rate of screening in the United States remains low at under 60% despite the benefits. 

    Many people avoid the screening because they do not want to undergo a colonoscopy, the gold standard for colorectal screening. A colonoscopy is the only screening procedure that allows the physician to visualize the entire colon and remove abnormal growths that may be precancerous that are called polyps. The reason some people choose to not screen for colon cancer with a colonoscopy is because it requires the patient to intensely cleanse the bowels before the procedure while following a diet that restricts many foods and medications.

    At home colon cancer screening stool tests are an effective method in detecting polyps and abnormal growths for those at low risk.

    Can You Test Yourself For Colon Cancer?

    An option for those who are hesitant to get a colonoscopy is at home colon cancer tests. Studies show that at home colon cancer screening tests have helped to increased screening rates. These tests are known as fecal blood tests  and they are usually available by prescription only. There are tests available over the counter that test for colon cancer, however they are not approved by the FDA as an official screening test. 

    What Are At Home Colon Cancer Tests?

    At home colon cancer tests are screening tests that you take at home that test for hidden blood and, in one particular test, the DNA of your stool sample. Fecal blood tests detect hidden blood in the stool that may be from precancerous polyps or colon cancer itself. The at home colorectal screening tests that are approved by the Food and Drug Administration (FDA) are:

    • Guaiac fecal occult blood test (gFOBT)
    • Fecal immunochemical test (FIT)
    • Multitarget stool DNA test (FIT-DNA)

    Guaiac fecal occult blood test (gFOBT)

    The guaiac fecal occult blood test (gFOBT) uses the chemical guaiac to detect the presence of blood components found in the heme protein of our red blood cells. Guaiac is an antioxidant chemical that is extracted from the wood resin of the Guaiacum tree native to the Bahamas. Chemists use this chemical to detect microscopic amounts of blood by a simple reaction involving hydrogen peroxide. 

    Guaiac reacts not only with heme but with chemicals found in plants. People who are taking the test have to abstain from iron supplements, red meat, certain vegetables, vitamin C, and citrus fruit for several days before the test. The test is completely noninvasive and only requires you take a sample of your stool after you use the bathroom. You will need to take samples from three separate bowel movements. After you follow the instructions with your kit you will mail the sample envelope to the lab to be analyzed. 

    Heme is found in the blood of all red-blooded animals and older versions of the test would result in a large number of the test returning false positive for blood if the person ate red-blooded meat like steak or hamburgers.The most current version of the guaiac stool test is known as the high-sensitivity gFOBT due to its ability to specifically detect the heme protein found in human blood only. For this reason, people who take this version of the test can still eat red meat but it is not recommended. 

    Fecal Immunochemical Test (FIT)

    Like all the gFOBT stool tests, the fecal immunochemical tests examine stool samples for the presence of microscopic amounts of blood that cannot be seen with the naked eye. FIT is sometimes referred to as iFOBT or immunochemical fecal occult blood test and is named after the chemical process used in the lab that is derived from the immune system.

    Instead of using a chemical to detect the presence of blood, FIT uses antibodies to detect the blood protein globin found in hemoglobin. The FIT is done the same as the guaiac stool test, except without the dietary or drug restrictions. You will collect a stool sample according to the directions on the kit and mail your sample to the lab listed on your kit. Once the sample reaches the lab it is sent to a pathologist who will test the stool sample with antibodies for the presence of the globin protein. 

    The lab component of the fecal immunochemical test is more complicated than the simple color-changing guaiac stool tests. In the lab, the sample is analyzed by using antibodies that specifically attach to the globin protein component of the hemoglobin molecule. If the antibodies bond with the blood protein then the pathologists know blood is present in the stool sample. The test is highly sensitive to low concentrations of globin and does not interfere with medications or foods.

    Multitarget stool DNA test (FIT-DNA or Cologuard™)

    The multitarget stool DNA test detects colon cancer by identifying DNA markers and occult blood in stool samples. The test is manufactured by the research corporation Exact Sciences and goes by the trade name Cologuard. It is actually a combination of two tests, the fecal immunochemical test discussed previously and a DNA screening test 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).  

    You are not required to change your diet or medications before this test. Once you collect a sample of your stool, you will send or drop off your sample to a lab. The lab will return the results to your physician or healthcare provider who will contact you with the results as soon as they arrive. This test is considered the most accurate stool blood test because it can not only detect blood in the stool from bleeding polyps, but also several cancer cell lines of colon cancer itself.

    What Are the Limitations?

    At home colon cancer tests that detect blood or abnormal cells in the stool are typically looking for the presence of a polyp, an abnormal tissue growth that may bleed when stool passes over its fragile surface. At home colorectal cancer screenings tests prescribed by physicians are accurate in detecting bleeding that stems from large adenomas and colorectal cancer. However, at home screening tests are not intended to replace a diagnostic colonoscopy or a surveillance colonoscopy in those patients who are at an elevated risk for developing colon cancer. There are limitations to the tests that are important to consider before deciding which test is best for you. These include:

    • If you receive a positive result from an at home test you will be advised to get a colonoscopy to rule out colon cancer
    • A colonoscopy that is a follow-up from a positive result is considered diagnostic, which mean you have to pay for the procedure even if you have insurance
    • At home screening tests are not accurate in finding small polyps or polyps of a unique shape (flat and toothed or sessile serrated)
    • gFOBT has a high false positive rate especially if you do not follow recommendations that limit certain foods and medications
    • A colonoscopy is repeated every ten years whereas a stool test may be required every year
    • An at home screening test may detect the presence of a polyp, but you need a colonoscopy for the polyp to be removed and analyzed by a pathologist

    Who Is the Test Good For?

    You have several options for screening for colon cancer, including a colonoscopy and home colon cancer stool tests. Talk to your doctor about these options to decide which test your physician deems as the right fit for you. If you are healthy, have no prior family or personal history of colon cancer, and do not have any signs or symptoms of bowel problems then an at home screening test may be an option for you. 

    Talk to your doctor about these options to decide which test your physician deems as the right fit for you. If you are healthy, have no prior family or personal history of colon cancer,  and do not have any signs or symptoms of bowel problems then an at home screening test may be an option for you. 

    Your doctor will typically consider your risk for colon cancer when deciding the best screening option for you. You are recommended to get an at home colorectal cancer screening if you are at an average risk. You are considered at ‘average risk’  if you do not have any of the following:

    • Family history of colorectal cancer
    • Personal history of colorectal cancer or polyps
    • Personal history of inflammatory bowel disease, including ulcerative colitis or Crohn’s disease
    • Personal history of receiving radiation therapy to the abdomen or pelvic area for previous cancer treatment
    • Confirmed or suspected history of colorectal cancer syndrome that is hereditary, such as familial adenomatous polyposis (FAP) or Lynch syndrome

    Having one or more of these risk factors means that you are not recommended to screen for colorectal cancer at home. Instead, a colonoscopy is the preferred option because if a polyp or adenoma is found the gastroenterologist can immediately remove the abnormal tissue and test for malignant cells. 

    If you are at a low or average risk for colon cancer then an at home colon cancer screening may be a good choice for you. Check with your doctor and discuss the possibility for screening at home.

    Who Is the Test Not Good For?

    Colonoscopies are generally recommended for screening for colon cancer due to the fact that a gastroenterologist can remove polyps during the procedure that may become cancerous in time. However, many people prefer an at home stool test that is easy to take and involves little to no preparation. Of course, you should consult with your doctor which type of screening test is recommended for you, there are some cases in which the test is not good for you. 

    The primary reason your doctor may dissuade you from choosing an at home test over a colonoscopy is dependent upon your risk factor for developing colon cancer. A major risk factor for colon cancer is based on your personal and familial medical history. Remember that if you have a family member who has had colon cancer you are at a higher risk for developing colon cancer. In fact, 20% of people diagnosed with colorectal cancer have a family member who has had colon cancer. This means that if you have a first degree relative (like your parent, sibling, or grandparent) with colon cancer you are typically not advised to screen using an at home stool test. 

     There are several risk factors that put people at a higher risk for developing colon cancer: 

    • Advanced age in men and women
    • Personal history of diverticulosis
    • Personal history of inflammatory bowel disease, ulcerative colitis, or Crohn’s disease
    • Prior abdominal or pelvic surgery
    • Higher number of adenoma growths
    • Family history  of colorectal cancer
    • Family history of inherited colorectal syndromes, including Lynch syndrome and Incomplete removal of adenoma and/or polyp
    • People who have poor economic resources
    • African-American descent
    • Hispanic descent

    If you have one or more of the above risk factors, you probably are considered at a higher risk and a colonoscopy may be the best option for you. 

    How Can I Get One?

    Make an appointment with your primary healthcare provider to discuss your options for colon cancer screening, including at home testing options. There are at home stool tests for sale in pharmacies and online that are over the counter. These tests are generally quite inexpensive and follow the same protocol that is used for prescribed stool tests. Some of these over the counter tests do not need to be mailed in to the lab for analysis but are examined by you for a simple color change to detect the presence of blood. These tests are typically not considered as a true screening by health professionals, but there is no  harm in taking the test.

    If you are interested in the tests approved by the FDA, including the gFOBT, FIT, and FIT-DNA tests, ask your physician directly and request a prescription for the one you both decide to be the most appropriate. Follow the directions closely to minimize the chance of receiving a false positive or false negative result. Keep in mind that if you do receive a positive result you will most likely be asked to follow up with a colonoscopy. 

    References

    American Cancer Society. (2020, November 17). American Cancer Society guidelines for colorectal cancer screening. Retrieved from American Cancer Society: https://www.cancer.org/cancer/colon-rectal-cancer/detection-diagnosis-staging/acs-recommendations.htm

    Cooper, L. (2016, December 01). At-home colon cancer tests: What you need to know. Retrieved from Consumer Reports: https://www.consumerreports.org/colonoscopy/at-home-colon-cancer-tests/

    Felson, S. (2020, July 24). Colon cancer screening guidelines. Retrieved from WebMD: https://www.webmd.com/colorectal-cancer/guide/colon-cancer-screening-guidelines#1-2

    Mann, D. (2021, May 20). Risk factors that raise odds for early-onset colon cancer. Retrieved from WebMD: https://www.webmd.com/colorectal-cancer/news/20210520/risk-factors-that-raise-odds-for-early-onset-colon-cancer

    Mayo Clinic Staff. (2014, December 03). Cologuard primed to change landscape of CRC screening. Retrieved from Mayo Clinic: https://www.mayoclinic.org/medical-professionals/digestive-diseases/news/cologuard-primed-to-change-landscape-of-crc-screening

    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

    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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