Colorectal Cancer Screening

Cancer in the bowel (colon) can be deadly. It is recommended that everyone over the age of 50 have a screening test to identify early-stage colon cancer and precancerous lumps called polyps. Over time, some polyps can develop into cancer. Available screening tests include colonoscopy, CT colonography (also known as virtual colonoscopy), double contrast barium enema, and stool-based tests like the fecal occult blood test, which looks for blood in the stool. Colonoscopy, CT colonography, and double contrast barium enema screen for both polyps and cancer, but stool-based tests screen only for cancer. CT colonography and barium enema expose the patient to ionizing radiation but do not require sedation and carry less risk of accidentally piercing the colon wall compared with colonoscopy. During colonoscopy, the physician can remove polyps and get biopsies of suspicious areas. All of the tests that visualize the colon require pretest bowel cleansing to remove stool from the colon.

People may be at average risk, moderate risk, or high risk for colon cancer based on family history and pre-existing conditions such as ulcerative colitis, Crohn's colitis, or Lynch syndrome. For average- and moderate-risk adults, the appropriate imaging screening test is CT colonography every 5 years. Double contrast barium enema is less commonly used. If suspicious polyps are seen on a CT colonography, a colonoscopy is recommended to get a biopsy. For high-risk adults, imaging screening tests are not recommended because often there is the need to do a biopsy. In these individuals, colonoscopy is the recommended test. The CT colonography test is appropriate after a positive fecal occult blood test or an incomplete colonoscopy.

For more information, see the Colorectal Cancer Screening page.

— By Celena Romero, RD, MBA, CPHQ, and Ryan K. Lee, MD, MBA, MRMD. This information originally appeared in the Journal of the American College of Radiology.