Effect of flexible sigmoidoscopy-based screening on colorectal cancer incidence and mortality: an updated systematic review and meta-analysis of randomized controlled trials

ObjectiveOur objective was to estimate the effect of flexible sigmoidoscopy (FS)-based screening on colorectal cancer (CRC) incidence and mortality by conducting an updated meta-analysis of randomized controlled trials (RCTs).MethodsPubMed, Web of Science, Embase, and Cochrane Library searched for RCTs from database inception to December 2022. The methodological quality of the RCTs was assessed using the Cochrane Collaboration Risk of Bias Tool. RevMan 5.4 was used for this meta-analysis.ResultsFour RCTs involving 457, 871 patients were included. This meta-analysis revealed that FS-based screening was associated with a 20% relative risk reduction in CRC incidence [RR = 0.80; 95% CI (0.75, 0.86); P < 0.00001], and a 24% reduction in CRC mortality [RR = 0.76; 95% CI (0.70, 0.82); P < 0.00001]. In addition, this meta-analysis revealed that FS-based screening reduced the incidence[RR = 0.68; 95% CI (0.60, 0.77); P < 0.00001] and mortality[RR = 0.64; 95% CI (0.49, 0.83); P = 0.0007] of distal CRC, but had no significant effect on proximal colon cancer.ConclusionFS-based screening appeared to be effective in reducing distal CRC incidence and mortality in patients at average risk compared to no intervention, but had no significant effect on proximal colon cancer.