Colorectal Cancer Screening Revisited
New Guidelines Call for More Vigorous Screening
Feb. 3, 2003 -- New colorectal cancer screening guidelines released today emphasize the need to start screening at age 50, but scale back the frequency of surveillance or follow-up screening for most people who have already had potentially pre-cancerous growths in their colon removed.
Researchers say that while awareness of the disease has grown since the first colorectal screening guidelines were published in 1997, screening rates still remain low. That's why the new guidelines, published by the U.S. Multisociety Task Force on Colorectal Cancer, stress the importance of widespread screening for everyone once they reach 50.
The authors say studies show that early screening is the best way to improve survival among people with colorectal cancer. A person's first colonoscopy detects the largest and most dangerous growths or polyps, which can then be removed during the same procedure.
Previous guidelines recommended that people who have had polyps removed should have follow-up colonoscopies for evaluation of additional growths every three years. But experts say recent research suggests that dangerous polyps are unlikely to develop in such a short time. The new guidelines suggest that patients who have had small polyps removed (less than 1 cm) have their first follow-up colonoscopy five years, rather than three years, after the initial procedure.
The revised guidelines appear in the February issue of Gastroenterology. They also say that those who have had advanced or three or more polyps should still have a follow-up colonoscopy every three years, as previously recommended.
The guidelines also place a greater emphasis on the use of colonoscopy for screening and surveillance as opposed to other methods. The procedure involves inserting a thin, flexible scope equipped with a small video camera through the rectum, which allows the physician to view the inside of the large intestine, where cancer is found.
Although colonoscopy is more expensive and less convenient than other methods, researchers say it allows them to see the entire colon and detect and remove polyps in one procedure.
The new guidelines call for using colonoscopy rather than barium enema for diagnosing the disease and screening people considered at high risk for colorectal cancer, such as those with a close relative with the disease, genetic risk factors, or a history of polyps.
Researchers say barium enema is less sensitive than colonoscopy and detects only about half of colon polyps, including large ones. But if this method is used, the new guidelines recommend screening every five years instead of every 10 years as previously recommended. The new guidelines also recommend against using the rehydrating fecal occult blood test -- take-home cards frequently given to patients -- as a screening aid.
But the guidelines' authors say two new tests currently under investigation, virtual colonoscopy and a DNA stool test, may allow for more effective and less invasive colorectal cancer screening in the future.
The lead author says if the guidelines were adopted nationwide, critical resources would be shifted from surveillance to screening -- leading to screening of more people and saving more lives.
SOURCE: Gastroenterology, February 2003 • WebMD Medical Reference with Healthwise: "Colonoscopy: Test Overview."