Colon cancer screening
Screening for colon cancer; Colonoscopy - screening; Sigmoidoscopy - screening; Virtual colonoscopy - screening; Fecal immunochemical test; Stool DNA test; sDNA test; Colorectal cancer - screening; Rectal cancer - screeningColon cancer screening can detect polyps and early cancers in the large intestine. This type of screening can find problems that can be treated before cancer develops or spreads. Regular screenings may reduce the risk for death and complications caused by colorectal cancer.
Colon cancer
Colorectal cancer is cancer that starts in the large intestine (colon) or the rectum (end of the colon). Other types of cancer can affect the colon. ...

Polyps
A colorectal polyp is a growth on the lining of the colon or rectum.

Information
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.
- The most common test used is the fecal occult blood test (FOBT). Two other tests are called the fecal immunochemical test (FIT) and stool DNA test (sDNA).
Fecal occult blood test
The stool guaiac test looks for hidden (occult) blood in a stool sample. It can find blood even if you cannot see it yourself. It is the most commo...
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Sigmoidoscopy
Sigmoidoscopy is a procedure used to see inside the sigmoid colon and rectum. The sigmoid colon is the area of the large intestine nearest to the re...

- 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 an exam that views the inside of the colon (large intestine) and rectum, using a tool called a colonoscope. The colonoscope has a sm...

- 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.
Virtual colonoscopy
Virtual colonoscopy (VC) is an imaging or x-ray test that looks for cancer, polyps, or other disease in the large intestine (colon). The medical nam...
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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.
Capsule endoscopy
Endoscopy is a way of looking inside the body. Endoscopy is often done with a tube put into the body that the doctor can use to look inside. Anothe...
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SCREENING FOR AVERAGE-RISK PEOPLE
There is not enough evidence to say which screening method is best. But, colonoscopy is most thorough. Talk to your provider about which test is right for you.
Both men and women should have a colon cancer screening test starting at age 50. Some providers recommend that African Americans begin screening at age 45.
With a recent increase in colon cancer in people in their 40s, the American Cancer Society recommends that healthy men and women start screening at age 45. Talk to your provider if you're concerned.
Screening options for people with an average risk for colon cancer:
- Colonoscopy every 10 years starting at age 45 or 50
- FOBT or FIT every year (colonoscopy is needed if results are positive)
- sDNA every 1 or 3 years (colonoscopy is needed if results are positive)
- Flexible sigmoidoscopy every 5 to 10 years, usually with stool testing FOBT done every 1 to 3 years
- Virtual colonoscopy every 5 years
SCREENING FOR HIGHER-RISK PEOPLE
People with certain risk factors for colon cancer may need earlier (before age 50) 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).
Ulcerative colitis
Ulcerative colitis is a condition in which the lining of the large intestine (colon) and rectum become inflamed. It is a form of inflammatory bowel ...
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Crohn disease is a disease where parts of the digestive tract become inflamed. It most often involves the lower end of the small intestine and the be...
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Screening for these groups is more likely to be done using colonoscopy.
References
Garber JJ, Chung DC. Colonic polyps and polyposis syndromes. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 126.
National Cancer Institute website. Colorectal cancer screening (PDQ) – health professional version. www.cancer.gov/types/colorectal/hp/colorectal-screening-pdq. Updated March 17, 2020. Accessed November 13, 2020.
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 June 15, 2016. Accessed April 18, 2020.
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/.
Colon cancer screening
Animation
Colonoscopy - illustration
There are 3 basic tests for colon cancer; a stool test (to check for blood), sigmoidoscopy (inspection of the lower colon), and colonoscopy (inspection of the entire colon). All 3 are effective in catching cancers in the early stages, when treatment is most beneficial.
Colonoscopy
illustration
Large intestine anatomy - illustration
One of the important jobs of the large intestine is to absorb the remaining water from the food residue passing through the intestines. The residue that is left remains in a semisolid state and is propelled toward the rectum by peristalsis. Through reflexes which are triggered by a full colon, feces is eliminated from the body.
Large intestine anatomy
illustration
Sigmoid colon cancer - X-ray - illustration
A barium enema in a patient with cancer of the large bowel (sigmoid area).
Sigmoid colon cancer - X-ray
illustration
Fecal occult blood test - illustration
A fecal occult blood test is a noninvasive test that detects the presence of hidden blood in the stool. Blood in the stool that is not visible is often the first, and in many cases the only, warning sign that a person has colorectal disease, including colon cancer.
Fecal occult blood test
illustration
Colonoscopy - illustration
There are 3 basic tests for colon cancer; a stool test (to check for blood), sigmoidoscopy (inspection of the lower colon), and colonoscopy (inspection of the entire colon). All 3 are effective in catching cancers in the early stages, when treatment is most beneficial.
Colonoscopy
illustration
Large intestine anatomy - illustration
One of the important jobs of the large intestine is to absorb the remaining water from the food residue passing through the intestines. The residue that is left remains in a semisolid state and is propelled toward the rectum by peristalsis. Through reflexes which are triggered by a full colon, feces is eliminated from the body.
Large intestine anatomy
illustration
Sigmoid colon cancer - X-ray - illustration
A barium enema in a patient with cancer of the large bowel (sigmoid area).
Sigmoid colon cancer - X-ray
illustration
Fecal occult blood test - illustration
A fecal occult blood test is a noninvasive test that detects the presence of hidden blood in the stool. Blood in the stool that is not visible is often the first, and in many cases the only, warning sign that a person has colorectal disease, including colon cancer.
Fecal occult blood test
illustration
- Colorectal cancer(Alt. Medicine)
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Review Date: 7/15/2020
Reviewed By: Michael M. Phillips, MD, Clinical Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.