The Importance of Screening
Screening means checking for health problems before they cause symptoms. Screening can find polyps that may eventually become cancerous (precancerous polyps), as well as some cancers in an early stage, before they spread to other parts of the body.
Colorectal cancer screening is used to detect cancer, precancerous polyps, or other abnormal conditions. If screening detects an abnormality, diagnosis and treatment can occur promptly. In addition, finding and treating polyps may be one of the most effective ways to prevent the development of cancer altogether. Colorectal cancer is generally more treatable when it is found early.Health care providers may suggest one or more of the tests listed on the following page for colorectal cancer screening.
Colorectal Cancer Screening Methods
- A fecal occult blood test (FOBT) checks for hidden blood in the stool. Studies have proven that this test, when performed every 1 to 2 years in people ages 50 to 80, reduces the number of deaths due to colorectal cancer by as much as 30 percent.
- 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. However, it is not known whether this benefit outweighs the risks of colonoscopy, which include bleeding and puncturing of the lining of the colon. More research is needed to address these issues.
- 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 may miss small polyps.
- A digital rectal exam (DRE) is often part of a routine physical examination. The health care provider inserts a lubricated, gloved finger into the rectum to feel for abnormal areas. DRE allows for examination of only the lower part of the rectum.
Scientists are still studying colorectal cancer screening methods, both alone and in combination, to determine how effective they are. Studies are also under way to clarify the risks of each test.
Which Exam Is Right for You?
Several major organizations, including the U.S. Preventive Services Task Force (a group of experts convened by the U.S. Public Health Service), the American Cancer Society, and professional societies, have developed guidelines for colorectal cancer screening. Although some details of their recommendations vary regarding which screening tests to use and how often to be screened, all of these organizations support screening for colorectal cancer.People 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:
- Person's 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; and
- Cost and insurance coverage of the test.