Background 

Flexible sigmoidoscopy (FS) has been recommended as a screening method to reduce mortality from colorectal cancer (CRC).

The present study evaluates the effect of adding FS to the fecal occult blood test Hemoccult-II (H-II) on diagnostic yield of colorectal neoplasia.

Methods 

A total of 10,978 normal persons aged 50-75 years were invited to participate, 5495 persons being allocated at random to H-Il and FS and 5483 to H-Il alone.

Results 

In spite of a lower compliance (40% versus 56%) for the combined procedure, the diagnostic yield of colorectal neoplasia was higher than for H-II alone (12 CRC versus 4 CRC, and 72 large adenomas versus 14).

Within 24-62 months after screening there were fewer CRCs detected after H-II+FS than after H-Il alone.

The stage distribution was less favorable than in screen-detected cases.

Conclusion 

One FS may not be an optimal way of screening, but FS deserves to be evaluated in randomized population studies including repeated H-II tests in the control arm.