For average risk individuals, a screening is recommended starting at age 50. African-Americans should start screening at 45.
People at a higher risk for colon cancer may need to start screening sooner and will require more frequent testing intervals.
If polyps (specifically a type of polyp called an adenoma) are found, then follow up surveillance with colonoscopy is recommended every 5 years. Shorter or longer intervals are dependent on the number, size, and character of the polyps identified.
For more detailed screening information, see the Colon Cancer Screening Tip Sheet.
Colon cancer can be prevented.
Several types of screening tests can be used to find polyps and colon cancer. Talk with your doctor about which option is right for you and the right time for you to be screened.
Stool based screening tests
There are several types of stool based screening tests that check for blood in your stool.They are called FOBT (sensitive guaiac test or sensitive fecal occult blood test) and FIT (fecal immunochemical test). These tests should be done once a year. A positive test requires further testing. A new test called Cologuard is also available as of 2014.
Colon screening tests
These tests allow doctors to check for polyps and cancer. They include the colonoscopy, flexible sigmoidoscopy, and virtual colonoscopy.
The only test that allows the doctor to check inside the entire colon and remove polyps. It is the single most reliable test for detection of polyps and cancer. Your doctor will examine the inside of your colon and rectum using a long, lighted tube called a colonoscope. Your doctor will check for abnormalities such as polyps. Generally, if a polyp is found, it can be removed with the scope. Removal of polyps is essential in prevention of colon cancer. A colonoscopy should be performed every 10 years in a normal risk person. If polyps are found during a colonoscopy or if the person is moderate or high risk for colon cancer, a more frequent evaluation may be needed. View diagram.
The doctor will examine the rectum and only the lower portion of the colon with a lighted tube. If polyps are found, a complete colon exam, such as colonoscopy will be needed to further evaluate the possibility of other polyps in higher regions of your colon unable to be reached by sigmoidoscopy. View diagram.
Images of the colon and rectum are taken using computerized tomography (CT). A computer puts the images together to create an animated, three-dimensional view. If abnormalities are detected, a colonoscopy is necessary. View diagram.
For any structural test, good bowel prep is essential to safely and accurately identify polyps. The goal of prep is to eliminate all fecal matter from the colon so that the physician conducting the exam will have a clear view. Your physician will instruct you to ingest a particular prep medication. We recommend doing a split dose. If you have significant heart, liver, or kidney problems, ask your physician whether you need specifically tailored preps. Drink lots of fluids to help avoid dehydration. All preparations will result in multiple bowel movements, so the evening before your exam, plan on being in a comfortable convenient location (near the bathroom).