Investigators from the USA investigated the prevalence of colorectal lesions in persons aged 40 to 49 years old, as identified on colonoscopy.
The procedure and pathology reports were reviewed for 906 consecutive persons who voluntarily participated in an employer-based screening-colonoscopy program.
The histologic features of lesions, that were identified and removed on endoscopy, were categorized.
This was done according to those of the most advanced lesion removed proximally (up to the junction of the splenic flexure and the descending colon) and the most advanced lesion removed distally.
|1 cancer detected in at least every 250 persons screened.
| New England Journal of Medicine |
An advanced lesion was defined as an adenoma at least 1 cm in diameter, a polyp with villous histologic features or severe dysplasia, or a cancer.
Among those who underwent colonoscopic screening, 79% had no detected lesions, 10% had hyperplastic polyps, 9% had tubular adenomas, and 4% had advanced neoplasms, none of which were cancerous.
Of the 33 advanced neoplasms, 55% were located distally and were potentially within reach of a sigmoidoscope.
The authors calculated that, if these results are applicable to the general population, at least 250 persons, and perhaps 1000 or more, would need to be screened to detect 1 cancer in this age group.
Dr Thomas F. Imperiale, of the Indiana University School of Medicine, Indianapolis, said on behalf of his group, "Colonoscopic detection of colorectal cancer is uncommon in asymptomatic persons 40 to 49 years of age.
"The non-cancerous lesions are equally distributed proximally and distally."
"The low yield of screening colonoscopy in this age group is consistent with current recommendations about the age at which to begin screening in persons at average risk," he concluded.