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ABSTRACT: Colorectal cancer is a significant contributor to morbidity and mortality in the United States. Studies published in the early 1990s, showing that screening for colorectal cancer can reduce colorectal cancer-related mortality, led many organizations to recommend screening in asymptomatic, average-risk adults older than 50 years. Since then, however, national screening rates remain low. Several important studies published over the past four years have refined our understanding of existing screening tools and explored novel means of screening and prevention. The most important new developments, which are reviewed in this article, include the following: Additional trial results support the effectiveness of fecal occult blood testing in reducing the incidence of, and mortality from, colorectal cancer. New studies document the sensitivity of fecal occult blood testing, sigmoidoscopy, and double-contrast barium enema compared with colonoscopy. Cost-effectiveness models show that screening by any of several methods is cost-effective compared to no screening. Randomized trials show that calcium is effective but fiber is not effective in preventing reoccurrence of adenomatous polyps. Preliminary data suggest that nonsteroidal anti-inflammatory drugs may prevent adenomatous polyps and that DNA stool tests and virtual colonoscopy may show promise as screening tools. This new information provides further support for efforts to increase the use of colorectal cancer screening and prevention services in adults older than 50 years.
ABSTRACT: Occult gastrointestinal bleeding usually is discovered when fecal occult blood test results are positive or iron deficiency anemia is detected. Fecal occult blood testing methods vary, but all have limited sensitivity and specificity. The initial work-up for occult bleeding typically involves colonoscopy or esophagogastroduodenoscopy, or both. In patients without symptoms indicating an upper gastrointestinal tract source or in patients older than 50 years, colonoscopy usually is performed first. About one half of patients with gastrointestinal bleeding do not have an obvious source of the bleeding. In those patients, small bowel imaging or repeat panendoscopy may be performed. Barium studies of the small bowel are widely available but have limited diagnostic utility. Mucosal lesions such as vascular ectasias, a common cause of obscure bleeding, may be missed by small bowel studies. Small bowel endoscopy is difficult to perform but has a higher diagnostic yield. Capsule endoscopy is a newer technique that allows noninvasive small bowel imaging. Radionuclide red blood cell scans or angiography may be useful in patients with active bleeding. Treatment of bleeding most often involves endoscopic ablation of the bleeding site with thermal energy, if the site is accessible. Angiographic embolization may be used to treat lesions that cannot be reached endoscopically. Diffuse vascular lesions, which are not uncommon, are difficult to treat. Medical treatment, usually with combined hormone therapy, has limited utility. Surgical treatment of obscure bleeding often fails or is not feasible because of multiple bleeding sites.
ABSTRACT: Colorectal cancer causes significant morbidity and mortality in the United States. The incidence of colorectal cancer can be reduced with increasing efforts directed at mass screening of average-risk adults 50 years and older. Currently, fecal occult blood test and flexible sigmoidoscopy have the highest levels of evidence to support their use for colorectal cancer screening. Colonoscopy does not have a proven colorectal cancer mortality benefit, but it does have the greatest single-test accuracy, and it is the final test in the pathway to evaluate and treat patients with other abnormal screening tests. Double-contrast barium enema has sparse data of effectiveness. Computed tomographic colonography, fecal DNA testing, and Pillcam Colon are promising tests that need further study before they can be recommended for widespread screening. Routine screening should continue until 75 years of age. There is good evidence that fiber and antioxidants are not effective for primary prevention of colorectal cancer; they should not be recommended for chemoprevention. There is good evidence that aspirin, nonsteroidal antiinflammatory drugs, and cyclooxygenase-2 inhibitors are effective for decreasing the risk of colorectal cancer and adenomatous polyps, but increased risks, such as gastrointestinal bleeding, limit their usefulness. There is fair evidence that obesity is associated with colorectal cancer. Additional studies are needed on decreased fat intake and red meat consumption, and the use of calcium, vitamin D, and statins before these can be recommended for primary prevention of colorectal cancer.
Screening for Colorectal Cancer: Recommendation and Rationale - U.S. Preventive Services Task Force
Colorectal Cancer Screening - FPIN's Clinical Inquiries
Fecal Occult Blood Tests Reduce Colorectal Cancer Mortality - Cochrane for Clinicians
ABSTRACT: Spurred by mounting evidence that the detection and treatment of early-stage colorectal cancers and adenomatous polyps can reduce mortality, Medicare and some other payors recently authorized reimbursement for colorectal cancer screening in persons at average risk for this malignancy. A collaborative group of experts convened by the U.S. Agency for Health Care Policy and Research has recommended screening for average-risk persons over the age of 50 years using one of the following techniques: fecal occult blood testing each year, flexible sigmoidoscopy every five years, fecal occult blood testing every year combined with flexible sigmoidoscopy every five years, double-contrast barium enema every five to 10 years or colonoscopy every 10 years. Screening of persons with risk factors should begin at an earlier age, depending on the family history of colorectal cancer or polyps. These recommendations augment the colorectal cancer screening guidelines of the American Academy of Family physicians. Recent advances in genetic research have made it possible to identify persons at high risk for colorectal cancer because of an inherited predisposition to develop this malignancy. These patients require aggressive screening, usually by lower endoscopy performed at an early age. In some patients, genetic testing can guide screening and may be cost-effective.