Published online Jan 7, 2018. doi: 10.3748/wjg.v24.i1.124
Peer-review started: November 3, 2017
First decision: November 21, 2017
Revised: December 12, 2017
Accepted: December 19, 2017
Article in press: December 19, 2017
Published online: January 7, 2018
Screening has shown to decrease colorectal cancer (CRC) incidence and mortality. Different screening guidelines for average-risk individuals have been issued worldwide, and several guidelines were published or updated recently. To our knowledge, this is the first systematic review aiming to summarize and compare worldwide CRC screening recommendations.
CRC screening recommendations for average-risk individuals differ greatly from one guideline to another, especially when it comes to choosing a preferred screening test. We aimed to compare those recommendations in order to highlight areas of uncertainty, and therefore orient future research by underlining areas where evidence is still lacking.
The main objectives were to compare screening recommendations in order to highlight common ground between guidelines, but also point out discrepancies caused by lack of high-quality evidence, making it easier to orient future research. Knowing which recommendations should clearly be perpetuated and which ones need further investigation can be helpful when it comes to updating guidelines or publishing new ones.
A systematic review of the literature was completed to identify all CRC screening guidelines for average-risk individuals published in English in the last ten years and/or position statements published in the last two years. Articles describing an established screening program without issuing recommendations, or articles only reviewing existing guidelines were excluded. Guidelines providing combined recommendations for average-risk and moderate/high-risk individuals, addressing only screening for moderate/high-risk individuals or older versions of existing guidelines were also excluded.
Fifteen guidelines were included, six of which were published in North America, four in Europe, four in Asia and one by the World Gastroenterology Organization (WGO). A majority of guidelines recommend screening average-risk individuals between ages 50 and 75. Preferred screening methods include colonoscopy (every 10 years), flexible sigmoidoscopy (FS - every 5 years), guaiac-based fecal occult blood test (gFOBT) or fecal immunochemical test (FIT), both repeated annually or biennially. FIT is often recommended over gFOBT, and combining FS with a stool based test is an option that should be considered. The role of colonoscopy varies greatly from one guideline to another, as some identify it as the screening gold standard whilst others highlight the lack of high-quality evidence supporting its use. Screening intervals as well as rank order between tests are also areas of uncertainty.
Average-risk individuals should undergo CRC screening between ages 50 and 75. Colonoscopy, FS, gFOBT and FIT are recognized as cost-efficient and currently recommended in a majority of guidelines, however their respective role and rank are not clearly established. Local resources availability and patient preferences should be considered when implementing a screening program, in order to maximize screening uptake, as any screening is better than none.
Establishing a clear ranking of screening methods rather than simply offering a menu of options could be useful in clinical practice. Future research should aim to provide high-quality evidence demonstrating screening tests efficiency, especially colonoscopy, in order to facilitate comparison between tests and help establishing such ranking. Screening intervals should be further investigated.