Barrett食道腺癌の内視鏡診断UPDATE

Endoscopic Diagnosis of Barrett's Esophageal Adenocarcinoma：Update

要旨●本邦でも日本食道学会の全国集計において全食道癌におけるBarrett食道腺癌（BAC）と食道腺癌を合わせた割合は2002年に2.4%，2012年には7.4%，さらに2016年には9.0%と約15年間で約4倍に増加しており，BACに対する内視鏡診断の重要性は増している．また本邦では欧米に比較しLSBEの頻度は少ないが，その発癌率に関しては同様である．BACをいかに発見し，深達度や範囲診断をどのように行っていくかが大切なポイントである．範囲診断にはNBI併用拡大内視鏡観察は必須であり，特にLSBE由来のBACは平坦病変が多く，JES-BE分類を用いて慎重に診断する必要があり，構造異型に重きを置き，必要ならば積極的に酢酸撒布を行う．さらに多発癌にも留意すべきである．深達度は早期胃癌と同様に肉眼型が重要であり，さらに病変の伸展性・可動性を評価し，NBI拡大観察による表面構造や血管構造の評価も有用である．

　In Japan, a nationwide survey conducted by the Japan Esophageal Society reported that the proportion of Barrett's esophageal adenocarcinoma（BAC）and other esophageal adenocarcinomas among all esophageal cancer cases has increased from 2.4% in 2002 to 7.4% in 2012 and 9.0% in 2016, representing approximately a fourfold increase over 15 years. Consequently, the importance of endoscopic diagnosis of BAC has been increasingly recognized. Although long-segment Barrett's esophagus（LSBE）is less prevalent in Japan than in Western countries, reports have indicated that its carcinogenic risk is comparable. Accurate detection of BE-derived BAC and precise determination of its invasion depth and lateral extent are therefore critical issues. For assessing the extent of diagnosis, magnifying endoscopy with narrow-band imaging（NBI）is essential, particularly because BACs arising from the LSBE often present as flat lesions. Careful evaluation using the JES-BE classification is required, with emphasis on structural atypia, and, when necessary, acetic acid chromoendoscopy should be actively employed. Attention should also be given to the possibility of multiple lesions. As for the invasion depth, macroscopic appearance, as in early gastric cancer, is an important determinant. Additionally, the assessment of lesion distensibility and mobility, along with the surface and vascular patterns by magnifying NBI, is useful.