Why Screen for Colorectal Cancer

Colorectal Cancer Screening Options



Colorectal cancer is one of the leading causes of death from cancer in the U.S.1 When colorectal cancer develops, malignant cells grow in either the colon or rectum. In the earliest stages, the cancer usually has no symptoms, which is why screening tests are so important.



Screening for colorectal cancer is a crucial part of preventive care. When you should start screening and the right test for you depends on your risk factors for cancer and your physician's recommendations. Learn more about your screening options for colorectal cancer.



Stool-Based Screening Tests



Stool-based screening tests are typically the least invasive option and are often recommended for people with the lowest risk of developing colorectal cancer.



Three types of stool-based screening tests are available. Two tests look for blood in the stool while the third analyses DNA. You can perform stool-based tests at home by collecting a sample and sending it into a lab.



The guaiac-based fecal occult blood test (gFOBT) and fecal immunochemical test (FIT) look for blood in your stool. Both tests can find blood in the stool that may not be visible to the eye. You can have the tests performed annually.



The other type of stool-based screen test looks at the DNA in your stool to see if there are any genetic changes. Sometimes, a DNA stool test can be combined with a stool blood test.



Sigmoidoscopy



During a sigmoidoscopy, a physician uses a thin, lighted tube to examine the rectum and lower part of the colon. The purpose of the test is to determine if there are any polyps or signs of cancer in the lower colorectal area.

Colonoscopy



During a colonoscopy, a physician examines the entire colon and rectum, using a thin, lighted tube. The test goes deeper into the colon than a sigmoidoscopy and is often performed as a follow-up if anything suspicious is found during the sigmoidoscopy or stool-based tests.



A physician can also remove a small polyp sample or other suspicious growth during a colonoscopy for further testing.

Depending on your family history and other risk factors, your family physician may recommend you undergo a colonoscopy and not less invasive screening options.



CT Colonoscopy



While a traditional colonoscopy requires the use of a physical scope to examine the colon, a CT colonoscopy uses CT imaging, a type of X-ray, to capture images of the inside of the colon. A CT colonoscopy can help detect polyps and other changes in the colon, but may not be able to detect smaller growths.



Depending on the results of a CT colonoscopy, you may need a follow-up with a standard colonoscopy to remove and test polyps.



How to Choose a Screening Option



With so many options for colorectal cancer screening, it can be tough to decide which is right for you. Fortunately, your family doctor can help you make a decision.



Often, the least invasive testing options, the DNA and blood stool tests, are only recommended for people who don't have a family history of colorectal cancer or who don't have other risk factors for cancer.



How likely you are to have the screening test performed can also influence your decision-making. Colonoscopies have a reputation for being uncomfortable and some people may not like the idea of having one performed, even if they have a higher risk for colon cancer. In that case, a less invasive test may be appropriate, as it will provide some form of screening.



When to Screen for Colorectal Cancer



When you should start screening for colorectal cancer also depends on your family history and other risk factors. Generally, the recommendation is for people to begin screening at age 45.2 You may need screening earlier if you have more risk factors.



How often you need to screen for colorectal cancer depends on the type of test. Generally, you only need to repeat image-based tests, such as a colonoscopy, every five to 10 years. Your family doctor can help you determine a screening schedule based on your health history and preferences.



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Sources:  

1. Colorectal Cancer Screening, Cancer, https://www.cancer.gov/types/colorectal/patient/colorectal-screening-pdq

2. Colorectal Cancer Screening Tests, Centers for Disease Control and Prevention, https://www.cdc.gov/cancer/colorectal/basic_info/screening/tests.htm



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