Role of narrow band imaging for diagnosis of early-stage esophagogastric cancer: Current consensus of experienced endoscopists in Asia-Pacific region

In Asian countries, squamous cell carcinoma is the most common type of esophageal cancer, and the incidence of gastric cancer remains have plateaued. To synthesize current information and to illustrate its clinical benefit of narrow band imaging (NBI) for diagnosis of superficial esophageal squamous carcinoma (SESCC) and early gastric cancer (EGC), a consensus conference was held by a panel of nine experts from Asian-Pacific countries. The expert's agreement suggested importance of interpretation of both vascular architecture and surface structure of the lesions and proper processor settings for endoscopic images. Zoom endoscopy was not regarded as absolutely necessary for detection of SESCC, but magnifying observation provided valuable information for characterization of detected lesions in the esophagus and the stomach. In general, NBI is useful for detection and characterization of SESCC, whereas it is beneficial mainly for characterization of EGC. Chromoendoscopy was found to be still worthwhile in certain situations, such as determination of the extent of SESCC by Lugol's staining, or detection and delineation of EGC by indigo carmine. NBI could replace chromoendoscopy in routine examination because it is easy to use and adds much information to conventional WLI, but it cannot eliminate chromoendoscopy when we make a final diagnosis for treatment decision-making. Consequently, the benefit of NBI or magnifying NBI is specific for the organ and the purpose of the examination, thus optimum indication and usage should be understood for maximum clinical benefit.