413 Flexible sigmoidoscopy and faecal occult blood testing (FOBT) reduce colorectal cancer (CRC) mortality

April 09, 2014

PEARLS 413, November 2013, written by Brian R McAvoy

Clinical question
How effective are flexible sigmoidoscopy and guaiac-based FOBT in screening for CRC?

Bottom line

There was high-quality evidence both flexible sigmoidoscopy and FOBT reduced CRC mortality when used as screening tools. Neither tool reduced all-cause mortality. The rate of major complications in the flexible sigmoidoscopy groups was 8 in 10,000. Although rates of major complications were lower in the FOBT studies (3 in 10,000), this was associated with follow-up investigations, including sigmoidoscopy.


Four trials compared FOBT to no screening and 5 trials compared flexible sigmoidoscopy to no screening. No studies compared the 2 methods directly. To show an effect of CRC screening on all-cause mortality, a very large number of individuals would need to be included; the present studies were underpowered regarding this endpoint. An evaluation of costs of screening was beyond the scope of this review.


CRC is the third most frequent cancer in the world. As the asymptomatic period is several years and a good prognosis is associated with early-stage diagnosis, screening has been implemented in many countries. Screening with FOBT and flexible sigmoidoscopy have been shown to reduce mortality from CRC in RCTs. Their comparative effectiveness on CRC mortality has, however, not been evaluated previously.

Cochrane Systematic Review

Holme O et al. Flexible sigmoidoscopy versus faecal occult blood testing for colorectal cancer screening in asymptomatic individuals. Cochrane Reviews, 2013, Issue 19. Art. No.: CD009259.DOI: 10.1002/14651858. CD009259.pub2. This review contains 9 studies involving 744,386 participants.

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