How can people and their health care providers decide which colorectal cancer screening test(s) to use?

People should talk with their health care provider about when to begin screening for colorectal cancer, what test(s) to have, the advantages and disadvantages of each test, how often to undergo colorectal cancer screening, and when to stop.

The decision about which test to have usually takes into account several factors, including:

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  • The person’s age, medical history, family history, and general health
  • The potential harms of the test
  • The preparation required for the test
  • Whether sedation may be needed for the test
  • The follow-up care needed after the test
  • The convenience of the test
  • The cost of the test and the availability of insurance coverage

The commonly used colorectal cancer screening tests all have advantages and disadvantages:

Fecal Occult Blood Test (guaiac FOBT or fecal immunochemical test)


  • No cleansing of the colon is necessary.
  • Samples can be collected at home.
  • Cost is low compared with other colorectal cancer screening tests.
  • There is no risk of damage to the lining of the colon.
  • No sedation is needed.


  • The test does not detect some polyps and cancers.
  • False-positive test results (i.e., the test suggests an abnormality when none is present) are possible.
  • Dietary restrictions are needed before guaiac FOBT.
  • Additional procedures, such as colonoscopy, may be needed if the test result shows blood in the stool.



  • For most patients, discomfort is minimal, and complications are rare.
  • The doctor may be able to perform a biopsy or polypectomy (removal of a polyp or adenoma) during the test, if necessary.
  • Less extensive cleansing of the colon is necessary for this test than for a colonoscopy.
  • Sedation is often not required.


  • Abnormal growths in the upper part of the colon will be missed because the test allows the doctor to view only the rectum and the lower part of the colon.
  • Bowel cleansing is needed before the test.
  • Medication and diet changes may be needed before the test.
  • There is a very small risk of bleeding or of tearing or perforation of the lining of the colon.
  • Additional procedures, such as colonoscopy, may be needed if the test finds an abnormality.
  • The availability of sigmoidoscopy has decreased substantially in the United States in recent years (10).