食道表在癌における深達度診断からみたB2血管の意義

The Significance of Type B2 Vessels by the Japan Esophageal Society Classification of NBI Magnifying Endoscopy for the Diagnosis of Invasion Depth of Superficial Esophageal Squamous Cell Carcinoma

要旨●2011年に日本食道学会拡大内視鏡分類が作成され，現在臨床の場で広く普及している．B1血管やB3血管の診断精度は高い一方で，B2血管を呈する病変の深達度はT1a-LPM〜T1b-SM2まで幅広く存在し，特にT1b-SM2癌を示す病変の割合が高くunder diagnosis症例が多い．そこでB2血管の領域性に着目し，その長径と深達度との相関を詳細に検討した．T1b-SM2癌におけるB2血管領域長径中央値は10mmであり，T1a-LPM癌（5mm）やT1a-MM/T1b-SM1癌（4mm）に比べて有意に大きい結果であった．さらに，B2血管領域をB2血管のみで構成されるpure typeとB1血管が混在するmixed typeに分類した多施設での検討でも，pure typeにおいてT1b-SM2癌のB2血管領域長径はT1a-LPM癌やT1a-MM/T1b-SM1癌より有意に大きい結果であった．今後B2血管による診断精度向上のためには，この領域性を加味した診断が有用である可能性が示された．

　The simplicity of the new magnifying endoscopic classification of the Japan Esophageal Society makes it the most useful diagnostic classification. However, despite the high diagnostic accuracy by Type B1 vessels，the distinction of Type B2 vessels using this diagnostic classification is slightly difficult. Typically, the tumor depth of lesions with Type B2 vessels exists widely from T1a-LPM to T1b-SM2, with particularly high ratio of lesions indicating T1b-SM2 cancer ; besides, there are many cases which are under diagnosis. Thus, this study focused on domain characteristics of Type B2 vessels and examined a correlation between the long axis and invasion depth. Compared with T1a-LPM cancer（5mm）and T1a-MM/T1b-SM1 cancer（4mm）, the invasion depth of Type B2 vessels was 10mm, with a significant domain longer axis median in T1b-SM2. We classified Type B2 vessels domains in the mixed type in which Type B1 vessels were mixed with the pure type comprising only Type B2 vessels. Furthermore, Type B2 vessels' domain longer axis of T1b-SM2 cancer was considerably more than that of T1a-LPM and T1a-MM/T1b-SM1 cancer. Perhaps, the incorporation of the domain characteristics of Type B2 vessels in the diagnostic classification to enhance the diagnostic precision could be useful in future as evident from the remarkable results of the pure type in several facilities.