Narrow-Band Imaging vs. Magnifying Chromoendoscopy for the Diagnosis of Early Colorectal Cancer Invasion Depth: Systematic Review and Meta-Analysis

Background and study aim: Optical assessment of deep submucosal invasion (T1b) in T1 colorectal cancer (CRC) is critical for selecting endoscopic versus surgical management. We conducted a systematic review and meta-analysis restricted to studies using a paired comparative design, in which narrow-band imaging (NBI) and magnifying chromoendoscopy (MCE) were applied to the same lesion during the same endoscopic session. Patients and methods: MEDLINE, Embase, and CENTRAL were searched from inception to September 19, 2025. Eligible studies compared NBI and MCE applied to the same lesions during the same endoscopic session, with histopathology as the reference standard and T1b defined as ≥1,000 µm. Two reviewers independently screened studies and extracted data; risk of bias was assessed using QUADAS-2 and QUADAS-C. Pooled sensitivity and specificity and between-modality differences were estimated using a Bayesian bivariate HSROC model. Prespecified subgroup analyses compared real-time diagnosis with image-based evaluation. Results: Ten studies comprising 2,814 lesions were included. Pooled sensitivity and specificity were 75.4% (95% credible interval [CrI] 63.2–85.3) and 94.5% (95% CrI 90.8–97.0) for NBI, and 79.8% (95% CrI 75.9–83.3) and 93.8% (95% CrI 91.6–95.6) for MCE. Direct comparisons indicated small differences in sensitivity and specificity, with uncertainty intervals including no difference. In subgroup analyses, real-time diagnosis showed higher sensitivity than image-based evaluation, while specificity was comparable. Conclusions: NBI and MCE show high accuracy for diagnosing deep submucosal invasion in T1 CRC, with no clear overall superiority in paired comparisons. Diagnostic setting may influence sensitivity and should be considered when translating optical diagnosis studies into practice.