食道表在癌肉眼分類の新しい提案―内視鏡の立場から

Endoscopic Classification of Superficial Esophageal Cancer

要旨　食道癌取扱い規約も初版以来20年に近く，改訂によりいろいろと改善されてきた．しかし，X線，内視鏡，病理肉眼型の分類は，各々その呼称が異なっていて不便を感じており，今回，できるだけ同じ分類を使うよう検討された．内視鏡型分類は内視鏡委員会の手で検討を進めたが，ほとんど病理肉眼型分類に準じた分類とした．大きく変わったところはないが，表在型の亜型分類に最近の内視鏡診断進歩の知見を取り入れ，0-Ⅰ（隆起），0-Ⅱ（平坦），0-Ⅲ（陥凹）と分けたうちで，0-Ⅱは肉眼型が平坦に近いものと同時に，深達度をmmまでと予測するもの（もちろんすべて組織診断と―致しない）を念頭に置いて記載するように考慮した．

　In analyzing the depth of superficial cancer related to nodal involvement and to vascular invasion, 16 out of 19 cases of mucosal cancer (84%) had neither nodal involvement nor vascular invasion. In contrast, 31 out of 104 cases of submucosal cancer (28%) had neither nodal involvement nor vascular invasion. The 5-year survival rate of the patients with superficial cancer with and without lymph node metastasis were 22% and 68%, respectively. The 5-year survival rate of the patients with mucosal cancer was 100%, while that for submucosal canser without nodal involvement was 71%. Based on these data, long-term survival is expected to be excellent in most cases of mucosal cancer. Superficial cancer of the esophagus is classified endoscopically as follows: 0-Ⅰ (superficial and protruded type), 0-Ⅱa (slightly elevated type), 0-Ⅱb (flat type), 0-Ⅱc (slightly depressed type), 0-Ⅲ (superficial and excavated type), and 0-Ⅴ (superficial and unclassified type). The advanced esophageal cancer is classified into 5 types endoscopically, i.e., 1 (protruded type), 2 (well-defined excavated type), 3 (ill-defined excavated type), 4 (diffusely infiltrating type) and 5 (unclassified type). Previous data from the endoscopic study on superficial cancer, the polypoid and the plateau-like types were mostly submucosal cancer. The ulcerative type was also submucosal cancer. Only the flat and the erosive lesions were mucosal cancer. According to the endoscopic classification of superficial cancer described above, mucosal cancer is expected to be in the type 0-Ⅱa, 0-Ⅱb or 0-Ⅱc.