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Colorectal Cancer Screening


What is colon cancer?

Colon cancer happens when cells that are not normal grow in your colon. These cells often form in polyps, which are small growths in the colon. Not all colon polyps turn into cancer. But most colon cancer starts in a polyp.

Colon cancer occurs most often in people older than 50.

Who should be screened for it?

Your risk for colorectal cancer gets higher as you get older. Experts recommend starting screening at age 45 for people who are at average risk.footnote 1 Talk with your doctor about your risk and when to start and stop screening.

How often you need screening depends on the type of test you get:

Stool tests.
Every year for FIT or gFOBT.
Every 1 to 3 years for sDNA, also called FIT-DNA.
Tests that look inside the colon.
Every 5 years for sigmoidoscopy. (If you do the FIT test every year, you can get this test every 10 years.)
Every 5 years for CT colonography (virtual colonoscopy).
Every 10 years for colonoscopy.

Experts agree that people at higher risk may need to be tested sooner and more often. This includes people who have a strong family history of colon cancer. Talk to your doctor about which test is best for you and when to be tested.



  1. U.S. Preventive Services Task Force (2021). Screening for colorectal cancer: U.S. Preventive Services Task Force recommendation statement. JAMA, 325(19): 1965–1977. DOI: 10.1001/jama.2021.6238. Accessed May 18, 2021.


Current as of: October 25, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.


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