Colon cancer screening
Screening for colon cancer; Colonoscopy - screening; Sigmoidoscopy - screening; Virtual colonoscopy - screening; Fecal immunochemical test; Stool DNA test; sDNA test
Colon 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 of death and complications caused by colorectal cancer.
There are several ways to screen for colon cancer.
- 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).
- 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 should be used together.
- A colonoscopy is similar to a sigmoidoscopy, but the entire colon can be viewed.
- 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.
- Double-contrast barium enema is a special x-ray of the large intestine that looks at the colon and rectum
- 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 which screening method is best. But, colonoscopy is most thorough. Talk to your doctor about which test is right for you.
Both men and women should have a colon cancer screening test starting at age 50. Some health care providers recommend that African Americans begin screening at age 45.
Screening options for people with an average risk for colon cancer:
- Colonoscopy every 10 years
- Double-contrast barium enema every 5 years
- FOBT every year (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 chronic inflammatory bowel disease (for example ulcerative colitis or Crohn disease).
Screening for these groups is more likely to be done using colonoscopy.
Itzkowitz SH, Potack J. Colonic polyps and polyposis syndromes. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease Pathophysiology/Diagnosis/Management. 10th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 126.
Lieberman DA, Rex DK, Winawer SJ, Giardiello FM, Johnson DA, Levin TR; United States Multi-Society Task Force on Colorectal Cancer. Guidelines for colonoscopy surveillance after screening and polypectomy: a consensus update by the US Multi-Society Task Force on Colorectal Cancer. Gastroenterology. 2012;143:844-57. PMID: 22763141 www.ncbi.nlm.nih.gov/pubmed/22763141.
National Cancer Institute: PDQ Colorectal Cancer Screening. Bethesda, MD: National Cancer Institute. Date last modified February 9, 2015. Available at: www.cancer.gov/types/colorectal/hp/colorectal-screening-pdq. Accessed October 7, 2015.
Reviewed By: Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.