White-light endoscopy versus magnifying narrow-band imaging for diagnosis of the histological subtype of gastric cancer

Objective: Distinguishing undifferentiated-type (diffuse-type) from differentiated-type (intestinal-type) cancer is crucial for determining the indication of endoscopic resection for gastric cancer. This study aimed to evaluate on-site diagnostic performance of conventional white-light endoscopy (WLE) and magnifying narrow-band imaging (M-NBI) in determining the subtype of gastric cancer. Design: We conducted a multicenter prospective single-arm trial. Patients who planned to undergo treatment for histologically proven cT1 gastric cancer were recruited from six tertiary care institutions. The primary and key secondary endpoints were diagnostic accuracy and specificity, respectively. The diagnostic algorithm of WLE was based on lesion color. The M-NBI algorithm was based on the microsurface and microvascular patterns. Results: A total of 208 patients were enrolled. After protocol endoscopy, 167 gastric cancers were included in the analysis. The accuracy, sensitivity, specificity, and positive likelihood ratio of WLE for undifferentiated-type cancer were 80% (95% CI 73%-86%), 69% (53%-82%), 84% (77%-90%), and 4.4 (2.8-7.0), respectively. Those of M-NBI were 82% (75%-88%), 53% (38%-68%), 93% (87%-97%), and 7.2 (3.6-14.4), respectively. There was no significant difference in accuracy between WLE and M-NBI (p = 0.755), but specificity was significantly higher with M-NBI than with WLE (p = 0.041). Those of M-NBI combined with WLE were 81% (74%-87%), 38% (24%-54%), 97% (92%-99%), and 11.5 (4.1-32.4), respectively. Conclusion: M-NBI is more specific than WLE in distinguishing undifferentiated-type from differentiated-type gastric cancer and M-NBI combined with WLE is highly reliable (positive likelihood ratio >10). Trial registration number UMIN000032151.