Estimation of invasion depth of early colorectal cancer using EUS and NBI-ME: a meta-analysis

Endoscopic ultrasonography (EUS) and narrow band imaging-magnifying endoscopy (NBI-ME) are often used as diagnostic tools to estimate the depth of invasion in early colorectal cancer (CRC). The aim of this study was to compare NBI-ME with EUS in distinguishing between slight submucosal invasion (invasion depth < 1000 μm) and massive submucosal invasion in patients with early CRC, since slight submucosal invasion is currently considered as an indication for endoscopic resection.

For this meta-analysis, relevant studies were identified from PubMed, Embase, Web of Science, Scopus and the Cochrane Library databases between January 1997 and September 2016. Data on the yield of tumors were extracted, pooled, and analyzed by stata12.0 software. The sensitivity, specificity, positive likelihood ratio and negative likelihood ratio in differentiating slight submucosal invasion from massive submucosal invasion were calculated for both diagnostic modalities.

Sixteen studies involving 2197 lesions were included: nine were studies on EUS and 7 were studies on NBI-ME. The pooled sensitivity of EUS was 0.902 (95% CI 0.863-0.930), the specificity was 0.877 (95% CI 0.810-0.922), the positive likelihood ratio was 7.314 (95% CI 4.551-11.755) and the negative likelihood ratio was 0.112 (95% CI 0.076-0.164). The pooled sensitivity and specificity of NBI-ME were 0.981 (95% CI 0.949-0.993) and 0.651 (95% CI 0.600-0.699), respectively, the positive likelihood ratio was 2.815 (95% CI 2.432-3.258) and the negative likelihood ratio was 0.029 (95% CI 0.010-0.080).

The sensitivity tended to be higher in ME-NBI than EUS for early CRC with slight submucosal invasion, whereas the specificity was significantly lower in NBI-ME than in EUS.