Barrett食道および腺癌の拡大内視鏡診断─NBIを中心に

Magnification Endoscopy for Early Neoplasms in the Barrett's Esophagus

要旨●欧米においてBarrett食道腺癌は急増しているが，本邦では依然まれである．しかし，本邦において逆流性食道炎の罹患率は上昇しており，今後，Barrett食道および食道腺癌の増加が憂慮されている．進行した食道腺癌の予後は不良であり，患者予後の改善には内視鏡検査による早期診断が必要であるが，通常内視鏡検査のみでは難しい場合も少なくない．近年，NBI（narrow band imaging）をはじめとする先進的内視鏡画像技術を併用した拡大内視鏡診断の有用性が報告されるようになった．そこで，本稿ではNBIを中心としたBarrett食道表在癌に対する拡大内視鏡診断について，最新の知見を含め述べたい．

　BE（Barrett's esophagus）is a metaplastic condition that occurs as a result of gastroesophageal reflux disease. BE is also a precursor to esophageal adenocarcinoma, which, even though still rare in Japan, is one of the most rapidly increasing cancers in Western countries. However, over the past few decades the prevalence of gastroesophageal reflux diseases has significantly increased in Japan. This increase is likely to result in an incremental rise in BE and the associated inherent risk of adenocarcinoma.

　Because of the poor prognosis of late-stage adenocarcinoma in Barrett's esophagus, it is important to detect early neoplasias in BE patients. However, endoscopic identification of early neoplasms remains subjective and not sufficiently reliable, thus, making the targeted therapy extremely difficult.

　During the last decade, newly-developed imaging technologies combined with magnification endoscopy have enabled the identification of early neoplasias in BE patients. This article focuses on such advanced imaging technology, particularly, narrow band imaging, and provides an overview of the technologies, their practical applicability, current status, and future challenges.