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Clinical Index for Predicting Advanced Proximal Neoplasia

A useful clinical index based on known risk factors to stratify risk for advanced proximal neoplasia.

Current guidelines lump people with average risk for colorectal cancer (nearly 80 million people) into a single category and suggest that clinicians select a single strategy, such as colonoscopy or flexible sigmoidoscopy, for screening such patients. However, both adenomas and advanced adenomas are found more commonly in men than in women and increase in prevalence with age. Furthermore, adenomas and cancers shift into the proximal colon with advancing age. In this cross-sectional analysis of an industry-based, screening colonoscopy program in Indiana, researchers sought to identify patients at low-risk for advanced proximal neoplasia in whom sigmoidoscopy would suffice.

Researchers generated a clinical index to stratify risk for advanced proximal neoplasia; the risk was based on age, sex, and distal findings in 1994 consecutive asymptomatic adults (age, 50 or older). The findings in the distal colon as recorded during colonoscopy were used as surrogates for sigmoidoscopy findings. A score (0 to 7) was calculated by adding points for age (<55 years, 0; 55-59, 1; 60-64, 2; 65, 3), sex (female, 0; male, 1), and the most-advanced distal finding (no polyp, 0; hyperplastic polyp, 1; tubular adenoma <1 cm, 2; advanced lesion [defined as tubular adenomas >1 cm, any polyp with villous cytology or high-grade dysplasia, or cancer], 3). The index was validated in a subsequent group of 1031 people, among whom colonoscopy to the cecum was completed in 97%. Overall, 3.4% of patients in the derivation group and 1.45% of those in the validation group had advanced proximal neoplasia (P=0.002). Risk for advanced proximal neoplasia increased as the index score increased (from 0.43% for a score of 0, to 27.8% for a score of 7; or from 0.68% for a low-risk score of 0-1, to 10% for a high-risk score of 4-7).

Comment: These researchers provide a clever and useful quantification of known risk factors to predict advanced proximal neoplasm, but applying their scoring system requires the use of screening sigmoidoscopy. In many cases, sigmoidoscopy would be a step backward because of the associated discomfort and unwillingness of patients to undergo repeat examinations. However, as the authors note, the results suggest that sigmoidoscopy should be used for screening in women who are aged 50 to 60 and that colonoscopy makes more sense in men who are 60 or older. Although this strategy has been suggested before, this study provides useful quantification of its underlying principles.

— Douglas K. Rex, MD

Published in Journal Watch Gastroenterology February 3, 2004

Citation(s):

Imperiale TF et al. Using risk for advanced proximal colonic neoplasia to tailor endoscopic screening for colorectal cancer. Ann Intern Med 2003 Dec 16; 139:959-65.

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