Aim to unify the narrow band imaging (NBI) magnifying classification for colorectal tumors: current status in Japan from a summary of the consensus symposium in the 79th Annual Meeting of the Japan Gastroenterological Endoscopy Society.

At present, there are many narrow band imaging (NBI) magnifying observation classifications for colorectal tumor in Japan. To internationally standardize the NBI observation criteria, a simple classification system is required. When a colorectal tumor is closely observed using the recent high-resolution videocolonoscope, a pit-like pattern on the tumor can be observed to a certain degree without magnification. In the symposium we could have a consensus that we will name the pit-like pattern as 'surface pattern.' Using the NBI system, the microvessels on the tumor surface can also be recognized to a certain degree. When the NBI system is used, the structure is emphasized, and consequently, the surface pattern can be recognized easily. Recently, an international cooperative group was formed and consists of members from Japan, the USA and Europe, which is named as the Colon Tumor NBI Interest Group. This group has developed a simple category classification (NBI international colorectal endoscopic [NICE] classification), which classifies colorectal tumors into types 1-3 even by closely observing colorectal tumors using a high-resolution videocolonoscope (Validation study is now ongoing by Colon Tumor NBI Interest Group.). The key advantage of this is simplification of the NBI classification. Although the magnifying observation is the best for getting detailed NBI findings, both close observation and magnifying observation using the NICE classification might give almost similar results. Of course the NICE classification can be used more precisely with magnification. In this report we also refer the issues on NBI magnification, which should be solved as early as possible.