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Yield of Screening Colonoscopy Among 40- to 49-Year-Olds

These results support current recommendations to begin colorectal cancer screening at age 50 for people at average risk.

In the U.S., many authorities recommend colonoscopy as one option for cancer screening in average-risk people who are 50 or older. Now, even younger people inquire about the procedure, due to increasing public awareness of screening colonoscopy. In this study, researchers present outcomes of screening colonoscopy in 906 people, aged 40 to 49, whose employer offered the procedure as a reimbursable benefit.

No cancers were detected. Seventy-nine people (8.7%) had 1 or more tubular adenomas, and 32 (3.5%) had advanced adenomas (i.e., tubular adenomas at least 1 cm in diameter, villous adenomas, or polyps with high-grade dysplasia). Of 33 advanced lesions (1 person had 2 lesions), 15 were proximal to the descending colon, and 4 of these 15 were accompanied by a distal "sentinel" lesion. Thus, 11 people had proximal advanced lesions that would not have been detected by a screening program of sigmoidoscopy followed by colonoscopy for only patients with distal polyps.

Comment: Not surprisingly, the yield of colorectal cancer screening in this age group is fairly low. By comparison, among 2515 people aged 50 or older who also were screened during this study, 13 cancers were detected; advanced adenomas were found in about 4% of 50- to 59-year-olds and in about 8% of 60- to 69-year-olds. Although the authors acknowledge that colorectal cancer occasionally occurs in young people without risk factors, they conclude that their results are compatible with current recommendations to begin screening at age 50 for people at average risk.

— Allan S. Brett, MD

Published in Journal Watch General Medicine June 11, 2002

Citation(s):

Imperiale TF et al. Results of screening colonoscopy among persons 40 to 49 years of age. N Engl J Med 2002 Jun 6; 346:1781-5.

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