Colon cancer screening

SCREENING TESTS

There are several ways to screen for colon cancer.

Stool test:

• Polyps in the colon and small cancers can cause small amounts of bleeding that cannot be seen with the naked eye. But blood can often be found in the stool.
• This method checks your stool for blood.
• A common test used is the fecal occult blood test (gFOBT). Two other tests are called the fecal immunochemical test (FIT) and stool DNA test (sDNA) commonly known as Cologuard. 

Sigmoidoscopy:

• This test uses a small flexible scope to view the lower part of your colon. Because the test only looks at the last one third of the large intestine (colon), it may miss some cancers that are higher in the large intestine.
• Sigmoidoscopy and a stool test may be used together.

Colonoscopy:

• A colonoscopy is similar to a sigmoidoscopy, but the entire colon can be viewed.
• Your health care provider will give you the steps for cleansing your bowel. This is called bowel preparation.
• During a colonoscopy, you receive medicine to make you relaxed and sleepy.
• Sometimes, CT scans are used as an alternative to a regular colonoscopy. This is called a virtual colonoscopy.

Other test:

• Capsule endoscopy involves swallowing a small, pill-sized camera that takes a video of the inside of your intestines. The method is being studied, so it is not recommended for standard screening at this time.

SCREENING FOR AVERAGE-RISK PEOPLE

There is not enough evidence to say that any one screening method is best. Colonoscopy is the most thorough but also has the highest risk. Talk to your provider about which test is right for you.

All adults should have a colon cancer screening test starting at age 45.

Screening options for people with an average risk for colon cancer:

• Colonoscopy every 10 years starting at age 45
• gFOBT or FIT every year (colonoscopy is needed if results are positive)
• sDNA-FIT every 1 to 3 years (colonoscopy is needed if results are positive)
• Flexible sigmoidoscopy every 5 years or every 10 years plus stool testing with FIT done every year
• CT colonography (virtual colonoscopy) every 5 years

SCREENING FOR HIGHER-RISK PEOPLE

People with certain risk factors for colon cancer may need earlier (before age 45) or more frequent testing.

More common risk factors are:

• A family history of inherited colorectal cancer syndromes, such as familial adenomatous polyposis (FAP) or hereditary nonpolyposis colorectal cancer (HNPCC).
• A strong family history of colorectal cancer or polyps. This usually means close relatives (parent, sibling, or child) who developed these conditions younger than age 60.
• A personal history of colorectal cancer or polyps.
• A personal history of long-term (chronic) inflammatory bowel disease (for example, ulcerative colitis or Crohn disease).

Screening for these groups is more likely to be done using colonoscopy.

Screening for colon cancer; Colonoscopy - screening; Sigmoidoscopy - screening; Virtual colonoscopy - screening; Fecal immunochemical test; Stool DNA test; sDNA test; Colorectal cancer - screening; Rectal cancer - screening

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National Cancer Institute website. Colorectal cancer screening (PDQ) -- health professional version. www.cancer.gov/types/colorectal/hp/colorectal-screening-pdq. Updated June 29, 2023. Accessed July 16, 2023.

Rex DK, Boland CR, Dominitz JA, et al. Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer. Am J Gastroenterol. 2017;112(7):1016-1030. PMID: 28555630 pubmed.ncbi.nlm.nih.gov/28555630/.

US Preventive Services Task Force website. Final recommendation statement. Colorectal cancer: screening. www.uspreventiveservicestaskforce.org/uspstf/recommendation/colorectal-cancer-screening. Published May 18, 2021. Accessed July 15, 2023.

Wolf AMD, Fontham ETH, Church TR, et al. Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society. CA Cancer J Clin. 2018;68(4):250-281. PMID: 29846947 pubmed.ncbi.nlm.nih.gov/29846947/.

Updated by: Michael M. Phillips, MD, Emeritus Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Internal review and update on 07/16/2023 by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.