Screening individuals aged 40-49 years for colorectal cancer is unlikely to yield much useful information, according to a new report.

The recommended age for colonoscopy for adults at average risk is 50, based on the finding that there is a significant increase in colorectal cancer in the sixth decade of life. Nevertheless, it is also known that nearly 7 per cent of colorectal cancers occur in those younger than 50.

A review of the screening procedures and pathology reports for 906 volunteers for an employer-based colonoscopy screening programme confirmed that the prevalence of colorectal cancer in this age group is too low to justify routine screening.

Results showed that 78.9 per cent had no detectable lesions, 18.7 per cent had various benign polyps and 3.5 per cent had advanced neoplasms (abnormal cell growth), none of which were malignant. Of the 33 with neoplasms, 55 per cent were considered operable with a good prognosis.

The authors concluded that at least 250 individuals (maybe even 1000 or more) would need to be screened to detect just one malignancy in this age group (N Engl J Med, 2002; 346: 1781-5).