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World J Gastroenterol. 2014 Dec 28;20(48):18466-76. doi: 10.3748/wjg.v20.i48.18466.

Reduced incidence and mortality from colorectal cancer with flexible-sigmoidoscopy screening: a meta-analysis.

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Jennifer Shroff, Nirav Thosani, Sachin Batra, Sushovan Guha, Division of Gastroenterology, Hepatology and Nutrition, The University of Texas Medical School at Houston, 77030 TX, United States.



To conduct a systematic review and meta-analysis of published population-based randomized controlled trials (RCTs).


RCTs evaluating the difference in mortality and incidence of colorectal cancer (CRC) between a screening flexible sigmoidoscopy (FS) group and control group (not assigned to screening FS) with a minimum 5 years median follow-up were identified by a search of MEDLINE and EMBASE databases and the Cochrane Central Register for Controlled Trials through August 2013. Random effects model was used for meta-analysis.


Four RCTs with a total of 165659 patients in the FS group and 249707 patients in the control group were included in meta-analysis. Intention-to-treat analysis showed that there was a 22% risk reduction in total incidence of CRC (RR = 0.78, 95%CI: 0.74-0.83), 31% in distal CRC incidence (RR = 0.69, 95%CI: 0.63-0.75), and 9% in proximal CRC incidence (RR = 0.91, 95%CI: 0.83-0.99). Those who underwent screening FS were 18% less likely to be diagnosed with advanced CRC (OR = 0.82, 95%CI: 0.71-0.94). There was a 28% risk reduction in overall CRC mortality (RR = 0.72, 95%CI: 0.65-0.80) and 43% in distal CRC mortality (RR = 0.57, 95%CI: 0.45-0.72).


This meta-analysis suggests that screening FS can reduce the incidence of proximal and distal CRC and mortality from distal CRC along with reduction in diagnosis of advanced CRC.


Colorectal Cancer; Flexible sigmoidoscopy; Incidence; Meta-analysis; Mortality; Randomized control trials

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