早期胃癌粘膜切除の適応拡大の限界―病理の立場から

Endoscopic Mucosal Resection of Early Gastric Carcinoma: The Possibility of Extending its Indication-being Based on Pathological Study

要旨　早期胃癌の内視鏡的胃粘膜切除の適応限界をsm癌について検討した．外科的に切除されたsm癌551病変中sm_1a（粘膜筋板下より200μmまで），sm_1b（粘膜筋板下から粘膜下層を3等分した上1/3）までにとどまる236病変を中心にリンパ節転移，脈管侵襲の有無を検討した．その結果，30mm以下のsm_1a，高分化型腺癌で，Ⅰ型を除いた隆起型，陥凹型Ul（－）では内視鏡治療のみで根治が可能である．更に水平方向浸潤も考慮すればsm_1bの一部のもので根治できる可能性がある．すなわち，高分化型腺癌，Ⅱa型で垂直方向浸潤が500μm，水平方向浸潤が1,500μm，陥凹型Ul（－）高分化型腺癌で垂直方向浸潤500μm，水平方向浸潤1,500μmであればリンパ節転移がなく内視鏡治療のみで根治できる可能性が示唆された．すなわち，垂直方向浸潤500μmまでをsm₁と定義し，内視鏡治療適応拡大の限界とできる可能性がある．

　We examined the relationship between the degree of submucosal infiltration, lymph node metastasis and vascular invasion in resected sm carcinoma specimens of 551 cases. The degree of vertical submucosal infiltration was classified into four stages, namely, sm_1a, sm_1b sm₂ and sm₃. These findings suggested that, for deciding endoscopic therapy in sm carcinoma, the cases should be those of well differentiated adenocarcinoma of sm_1a, of 30 mm or smaller without ulceration except type I early gastric carcinoma. Considerring horizontal infiltration, EMR was indicated as curative in some sm_1b carcinoma cases. For deciding whether or not EMR should be carried out in sm carcinoma, the following indicators are useful: Well differentiated adenocarcinoma, Ⅱa type, degree of vertical sm invasion is 500μm, and degree of horizontal invasion is 1,500μm and Ⅱc type, degree of vertical sm invasion is 500μm, and degree of horizontal invasion is 1,500μm. These cases were no lymph node metastasis. However, these indicators are not valid if there is lymph node metastasis. Therefore, it can be said that there is a possibility that the indication for EMR can be extended to sm₁ cancers where the submucosal invasion is 500μm.