Mar. 6, 2008 he American Cancer Society, the American College of Radiology, and the U.S. Multi-Society Task Force on Colorectal Cancer (a group that comprises representatives from the American College of Gastroenterology, American Gastroenterological Association, and American Society for Gastrointestinal Endoscopy) have released the first-ever joint consensus guidelines for colorectal cancer screening.
The guidelines add two new tests to the list of recommended options: stool DNA (sDNA) and CT colonography (CTC), also known as virtual colonoscopy, and for the first time include a preference for screening tests that can not only detect cancer early but also detect precancerous polyps, as those tests provide a greater potential for cancer prevention through polyp removal.
The guidelines, which represent the most current scientific evidence and expert opinion available, also outline quality elements essential to each of the recommended testing methods.
In addition to the new tests, the focus on quality and the new delineation of tests into two major types, the expert panel also concluded that any proposed colorectal screening test that has not been shown in the medical literature to detect the majority of cancers present at the time of testing should not be offered to patients for colorectal cancer screening. That includes some types of previously endorsed guiaic-based stool tests.
Based on a review of the historic and recent evidence, the following tests were deemed acceptable options for the early detection of colorectal cancer and adenomatous polyps for asymptomatic adults aged 50 years and older:
Tests That Detect Adenomatous Polyps and Cancer
- Flexible sigmoidoscopy every 5 years, or
- Colonoscopy every 10 years, or
- Double contrast barium enema (DCBE) every 5 years, or
- CT colonography (CTC) every 5 years
Tests That Primarily Detect Cancer
- Annual guaiac-based fecal occult blood test (gFOBT) with high test sensitivity for cancer, or
- Annual fecal immunochemical test (FIT) with high test sensitivity for cancer, or
- Stool DNA test (sDNA), with high sensitivity for cancer, interval uncertain.
"Despite clear evidence that colorectal cancer screening saves lives and the existence of several effective tests, screening rates have lagged, costing thousands of lives every year," said Otis W. Brawley, M.D., national chief medical officer of the American Cancer Society. "Our hope is that these new recommendations will help relieve some of the challenges health care providers have had in promoting screening to their patients and lead to more Americans preventing colon cancer by having polyps removed before they turn into cancer."
It was the strong opinion of the expert panel that colon cancer prevention should be the primary goal of colorectal cancer screening, so the guidelines state a preference for tests designed to detect both early cancer and adenomatous polyps, as long as resources are available and patients are willing to undergo an invasive test. "This is the first time that a guideline from the American Cancer Society will express a strong preference for tests that can identify both polyps and cancer and lead to cancer prevention," noted David A. Lieberman, M.D., on behalf of the U.S. Multi-Society Task Force on Colorectal Cancer. "We feel strongly that this will help consumers make decisions that can, quite literally, save their lives."
The panel recognized that some patients will not want to undergo an invasive test that requires a bowel prep, may prefer to have screening in the privacy of their home, or may not have access to the invasive tests due to lack of coverage or local resources, so will opt for stool occult blood or DNA testing, which can be performed at home, without bowel prep. But the panel said providers and patients should understand that those tests are less likely to prevent cancer compared with the invasive tests; they must be repeated at regular intervals to be effective; and if the test is abnormal, an invasive test (colonoscopy) will still be needed.
"The addition of these new technologies can potentially encourage many more people to choose to be screened for colorectal cancer," said Arl Van Moore, M.D., FACR, chair of the American College of Radiology Board of Chancellors. "This could result in early detection of the disease for more patients, increasing the chance of successful treatment, and potentially reduce colorectal cancer deaths nationwide."
An article on the guidelines will appear in the May/June issue of CA: A Cancer Journal for Clinicians, and are published early online on CA First Look and will also be published in upcoming issues of the journals Gastroenterology and Radiology.
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