Possible Advantages and Drawbacks of Adding Flexible Sigmoidoscopy to Hemoccult-II in Screening for Colorectal Cancer: A Randomized Study

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-II and FS and 5483 to H-II 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-II 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.