OBJECTIVES: Total colonoscopy (TCS) has been anticipated as a new method for colorectal cancer screening. Although randomized control studies (RCTs) are ongoing, there has yet to be a conclusive result. We evaluated the effectiveness of TCS screening following the stepwise approach developed by the World Endoscopic Evaluation (WEO).

METHODS: The WEO approach is to assess test accuracy and test performance for each new technique. We performed a systematic review of select studies during each phase by using of MEDLINE and Cochrane Library. We compared test accuracy for detecting advanced neoplasia (AN)/colorectal cancer (CRC) between fecal immunochemical testing (FIT), flexible sigmoidoscopy (FS), and TCS. Test performance indicators were compared based on single-round RCTs and performed a meta-analysis based on intention-to-treat (ITT) and per-protocol analysis.

RESULTS: One study compared sensitivities between FIT, FS, and TCS which were simultaneously performed. The sensitivity for the AN detection was consistently higher in TCS than others, even if the AN size was changed. 14 RCTs of test performance as colorectal cancer screening were selected. In the ITT analysis, the TCS participation rate of the meta-analysis was lower than FIT (RR= 0.49, 95%CI:0.22-0.89) and FS (RR= 0.83, 95%CI: 0.78–0.88). Although the AN detection rate was higher than FIT (RR= 2.25, 95%CI:1.40-3.61) and FS (RR= 1.15, 95%CI: 0.88–1.51), CRC detection was higher but not statistically significant (FIT RR= 1.48, 95%CI:0.66-3.43; FS RR= 1.08 95%CI: 0.49–2.37). On the per-protocol analysis, AN and CRC detection rates were higher in TCS than others.

CONCLUSIONS: Although high sensitivity was confirmed in TCS screening, test performance as a screening program was insufficient because of the low participant rates. One RCT presented that the efficacy of TCS screening could not be obtained for the same reason. The test performance of RCT could predict the effectiveness of the screening program.