Methods for Colorectal Cancer Screening

Last Updated: June 1, 2003

Screening means checking for health problems before they cause symptoms.

Colorectal cancer screening is used to detect cancer, polyps that may eventually become cancerous, or other abnormal conditions. If screening detects an abnormality, diagnosis and treatment can occur promptly. Colorectal cancer is generally more treatable when it is found early.

What methods are used to screen people for colorectal cancer?
Health care providers may suggest one or more of the tests listed below for colorectal cancer screening.
- A fecal occult blood test (FOBT) checks for hidden blood in the stool. Studies have proven that this test, when performed every one to two years in people age 50 to 80, reduces the number of deaths due to colorectal cancer.

- A sigmoidoscopy is an examination of the rectum and lower colon using a lighted instrument called a sigmoidoscope. Sigmoidoscopy can find precancerous or cancerous growths in the rectum and lower colon. Studies suggest that regular screening with sigmoidoscopy after age 50 can reduce the number of deaths from colorectal cancer.

- A colonoscopy is an examination of the rectum and entire colon using a lighted instrument called a colonoscope. Colonoscopy can find precancerous or cancerous growths throughout the colon, including the upper part of the colon, where they would be missed by sigmoidoscopy. The risks of colonoscopy include bleeding and puncturing of the lining of the colon.

- A double contrast barium enema (DCBE) is a series of X-rays of the entire colon and rectum. The X-rays are taken after the patient is given an enema with a barium solution and air is introduced into the colon. The barium and air help to outline the colon and rectum on the X-rays. Research shows that DCBE is more effective at detecting larger growths than smaller ones.

Which test is best for you?
You should talk with their health care provider about when to begin screening for colorectal cancer, what tests to have, the benefits and risks of each test, and how often to schedule appointments.

The decision to have a certain test will take into account several factors:
• Your age, medical history, family history, and general health
• Accuracy of the test
• Risks associated with the test
• Preparation required before the test
• Sedation necessary during the test
• Follow-up care after the test
• Convenience of the test
Cost and insurance coverage of the test

Do insurance companies pay for colorectal cancer screening?
Insurance coverage varies. People should check with their health insurance provider to determine their colorectal cancer screening benefits. Medicare covers several colorectal cancer screening tests for its beneficiaries. Specific information about Medicare benefits is available on the Medicare Web site at http://www.medicare.gov/health/overview.asp on the Internet.

What happens if a colorectal cancer screening test shows an abnormality?
If screening tests find an abnormality, the health care provider will perform a physical exam and evaluate the person’s personal and family medical history. Additional diagnostic tests may be ordered. These may include X-rays of the gastrointestinal tract, sigmoidoscopy or colonoscopy. The health care provider may also order a blood test called a CEA assay to measure carcinoembryonic antigen, a protein that is sometimes present in higher levels in patients with colorectal cancer.

If an abnormal area is found during a sigmoidoscopy or colonoscopy, a biopsy is performed to determine if cancer is present.

Source: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

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