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New guidelines on colorectal cancer recommend shift of focus to comprehensive initial screening of patients age 50 years and older

New colorectal cancer screening and surveillance guidelines published by the U.S. Multisociety Task Force on Colorectal Cancer stress the importance of initial screening for people age 50 years and older and reduce the frequency of surveillance for the majority of patients who have had colon polyps removed. The updated guidelines are published in the February issue of Gastroenterology.

Studies suggest that initial colorectal cancer screening provides the best results. A patient’s first screening detects the largest, most dangerous polyps, which can be removed with colonoscopic polypectomy. Previous guidelines recommended that after polypectomy, patients should receive follow-up colonoscopies every 3 years. However, data show that follow-up colonoscopies after 3 years may not add significant benefit to many patients because polyps with important pathology are very unlikely to develop in that time period. The new guidelines recommend patients who have 1 or 2 small (less than 1cm) tubular adenomas have their first follow-up colonoscopy at 5 years. Patients with advanced or multiple adenomas (3 adenomas or more) should still have their first follow-up colonoscopy at 3 years, the same as recommended in previous guidelines.

"Planning follow-up surveillance of patients according to their risk for advanced adenomas is an especially important point in the new guidelines," stressed Sidney Winawer, M.D., lead author of the guidelines. "If adopted nationally, this would shift critical resources from surveillance to screening, helping us screen more people, which would in turn decrease incidence and mortality rates."

In addition to recommending risk stratification for post-polypectomy patients, the new guidelines differ from the earlier version in emphasizing colonoscopy for screening and surveillance. Colonoscopy is recommended instead of barium enema for diagnostic evaluation, for screening people with close relatives who have colorectal cancer or adenomatous polyps younger than age 60 years, for screening people with two affected close relatives, for screening people with possible genetic mutations predisposing them to colorectal cancer, and for surveillance after polypectomy or colorectal cancer resection.

"Colonoscopy allows us to visualize the entire colon, and to detect and remove polyps in one procedure. It’s invaluable in patients who are at high risk of developing colorectal cancer," said Douglas Rex, M.D., member of the Task Force.

Genetic counseling should guide genetic testing and considerations of colectomy for patients with family members carrying mutations. For instance, patients with familial adenomatous polyposis have a long-term cancer risk that approaches 100 percent. Family members of an affected patient who test negative are considered at average risk for colorectal cancer. Family members who test positive should be followed by sigmoidoscopy until they develop polyps, at which point the timing of a colectomy can be considered. Genetic testing in children can be delayed until age 10 years.

Yearly fecal occult blood testing is recommended for people age 50 years or older who are at average risk for colorectal cancer. Rehydration is not recommended: Although rehydration of the guaiac-based slides increases sensitivity, the readability of the test is unpredictable and substantially increases the false positive rate.

Guideline authors looked to the future with two new tests that are in development. Virtual colonoscopy (thin-section, helical computed tomography followed by off-line processing) can yield high-resolution, 3-dimensional images of the colon. Although the procedure is less invasive and has not caused major complications, its ability to detect colon polyps is not well established. It requires the same patient preparation as colonoscopy but neither biopsy nor polypectomy can be done. In addition, a new DNA stool test is under study that might be more sensitive than occult blood testing, but less so than colonoscopy.


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