Delineation of the extent of early gastric cancer by magnifying narrow-band imaging and chromoendoscopy: a multicenter randomized controlled trial

Background Accurate delineation of tumor margins is necessary for curative resection of early gastric cancer (EGC). The objective of this multicenter, randomized, controlled study was to compare the accuracy with which magnifying narrow-band imaging (M-NBI) and indigo carmine chromoendoscopy delineate EGC margins. Methods Patients with EGC >= 10mm undergoing endoscopic or surgical resection were enrolled. The oral-side margins of the lesions were first evaluated with conventional white-light endoscopy in both groups and then delineated by either chromoendoscopy or M-NBI. Biopsies were taken from noncancerous and cancerous mucosa, each at 5mm from the margin. Accurate delineation was judged to have been achieved when the histological findings in all biopsy samples were consistent with endoscopic diagnoses. The primary end point was the difference in rate of accurate delineation between the two techniques. Results Data on 343 patients were analyzed. The accurate delineation rate (95% confidence interval) was 85.7% (80.4 - 91.0) in the chromoendoscopy group (n = 168), and 88.0% (83.2 - 92.8) in the M-NBI group (n = 175; P = 0.63). Lower third tumor location (odds ratio [OR] 2.9; P = 0.01), nonflat macroscopic type (OR 4.4; P < 0.01), and high diagnostic confidence (OR 3.6; P < 0.001) were associated with accurate delineation, whereas use of M-NBI was not (OR 1.2; P = 0.39). Even after adjustment for identified confounders, the difference in accurate delineation between the groups was not significant (OR 1.0; P= 0.82). Conclusions M-NBI does not offer superior delineation of EGC margins compared with chromoendoscopy; the two methods appear to be clinically equivalent.