Colon Cancer Screening

The goal of colon cancer screening is to detect colon cancer at an early stage and remove colon polyps from the colon and rectum. Polyps are growths that form on the inside of the colon, and some types of polyps may become cancerous over time.

Screening for colon cancer is recommended for everyone beginning at age 45 if you are at average risk for developing colon cancer, and continuing until age 75. Screening after age 75 can be performed based on your health and prior screening results.

There are several types of screening tests for colon cancer. These tests can be either one-step tests such as colonoscopy, which can both detect colon cancer and remove colon polyps during the procedure, or two-step tests such that if the initial results are positive, then the second step requires colonoscopy to complete the screening process. The following are some of the more common screening tests:

Stool tests:

These tests detect unseen blood in the stool that may be due to bleeding from colon cancer or polyps. Options include fecal occult blood or fecal immunochemical test (FIT) every year, and a stool test that combines FIT plus stool DNA (that can be shed by colon cancer) every three years.

Tests that directly visualize all or part of the colon:

• Colonoscopy screening every 10 years if no polyps are found.
• An x-ray known as a CT colonography every 5 years.
• Flexible sigmoidoscopy every 5 years.
• Flexible sigmoidoscopy every 10 years plus FIT every year.

A colonoscopy looks at the inside of the entire colon and polyps can be removed during this procedure. Because precancerous polyps can be removed during colonoscopy, this procedure can prevent colon cancer.

When stool-based tests reveal abnormal results, a colonoscopy is usually required to further evaluate the colon and search for colon polyps and colon cancer.

Flexible sigmoidoscopy views the inside of the rectum and lower colon. Polyps can be removed during this procedure. However, a colonoscopy would be needed to find any additional polyps in other areas of the colon.

CT colonography is an X-ray scan of the colon. If any abnormalities are found, a colonoscopy is performed to remove polyps or identify colon cancer.

Other screening tests for colon cancer are currently being developed. With regular screening, colon cancer can potentially be prevented or detected at an early stage. It is important to review the screening options with your primary care provider or your gastroenterologist.