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Colorectal Cancer Screening (PDQ®)

Risks of Colorectal Cancer Screening

Screening tests have risks.

Decisions about screening tests can be difficult. Not all screening tests are helpful and most have risks. Before having any screening test, you may want to discuss the test with your doctor. It is important to know the risks of the test and whether it has been proven to reduce the risk of dying from cancer.

False-negative test results can occur.

Screening test results may appear to be normal even though colorectal cancer is present. A person who receives a false-negative test result (one that shows there is no cancer when there really is) may delay seeking medical care even if there are symptoms.

False-positive test results can occur.

Screening test results may appear to be abnormal even though no cancer is present. A false-positive test result (one that shows there is cancer when there really isn't) can cause anxiety and is usually followed by more tests (such as biopsy), which also have risks.

The following colorectal cancer screening tests have risks:

Fecal occult blood testing

The results of fecal occult blood testing may appear to be abnormal even though no cancer is present. A false-positive test result can cause anxiety and lead to more testing, including colonoscopy or barium enema with sigmoidoscopy.

Sigmoidoscopy

There can be discomfort or pain during sigmoidoscopy. Women may have more pain during the procedure, which may lead them to avoid future screening. Tears in the lining of the colon and bleeding also may occur.

Colonoscopy

Serious complications from colonoscopy are rare, but can include tears in the lining of the colon, bleeding, and problems with the heart or blood vessels. These complications may occur more often in older patients.

Virtual colonoscopy

Virtual colonoscopy often finds problems with organs other than the colon, including the kidneys, chest, liver, ovaries, spleen, and pancreas. Some of these findings lead to more testing. The risks and benefits of this follow-up testing are being studied.

Your doctor can advise you about your risk for colorectal cancer and your need for screening tests.

  • Updated: December 11, 2014