Routine colonoscopies can find colon cancer in its early stages. This screening test allows your doctor to carefully examine your colon for signs of polyps (abnormal growths on the inside surface of the colon that can grow into cancer).
While there are many types of colorectal cancer screening tests, colonoscopy is the only test that can find polyps and remove them. This means that a colonoscopy can both find and prevent colon cancer.
Your care team may recommend other screening tests depending on your personal circumstances.
Below, you can learn about the different types of screening tests for colorectal cancer.
A colonoscopy is a test that checks for polyps in your colon. During this test, a thin, flexible tube with a light and a video camera on its tip is placed in your colon. Colonoscopy is the best way to find polyps. For 24 hours before the test, you will be on a clear-liquid diet and medication to clear out your bowel. You are not awake during a colonoscopy. Your doctor usually can remove any polyps they find. They will send them to a pathologist (a doctor who looks at body tissue under a microscope to diagnose disease).
A flexible sigmoidoscopy is similar to a colonoscopy. The main difference is that your doctor uses a shorter tube to examine the lower part of your colon.
A virtual colonoscopy (VC) is also known as a CT colonography. VC is an alternate screening option for some people. A radiologist uses CT scan technology to create 2-D and 3-D images of the colon. It does not require sedation. VC has limitations, however. For example, it requires the same preparation as a conventional colonoscopy: a clear-liquid diet and medication to clear out the colon. In addition, if VC detects a polyp or other abnormality in the colon, you may need a colonoscopy to remove it. VC can sometimes miss small or flat polyps.
Bleeding in your colon or rectum can be a sign of colon cancer. This test finds blood in your feces (poop) that you cannot see. For 3 days in a row, you will put small samples of your poop on a special card. Then, you will send the cards to a lab for testing. During the 3 days, you must follow a special diet so we can be sure your test results are accurate.
A fecal immunochemical test (FIT) checks for colon cancer by finding blood in your feces (poop). You do not have to follow a special diet. FIT is also called an immunochemical fecal occult blood test.
A stool DNA test checks for cancer by looking for gene changes (mutations or variants) and blood in your stool (poop). You do not need to follow a special diet.