sm浸潤度分類からみた大腸sm癌の内視鏡治療の適応と限界

The Adoption of Endoscopic Therapy from the Viewpoint of the Degree of Submucosal Invasion in Early Colorectal Carcinoma

要旨　大腸sm癌の内視鏡治療の適応と限界について，sm浸潤度細分類と脈管侵襲，リンパ節転移から検討を行った．対象は当センターで1985年4月から1999年3月までの期間に経験した大腸sm癌323病変，脈管侵襲は164病変（50.8％）の陽性率を示し，リンパ節転移は全体で18病変（10.9％）に認められ，2群リンパ節転移も2病変（1.2％）に認めた．また脈管侵襲を伴わないsm癌にはすべてにリンパ節転移が認められなかった．sm細分類の検討では，sm_1c以深で脈管侵襲30％を超え，1群リンパ節転移を認めた．肉眼形態ではsm深部浸潤傾向の強いⅡa＋Ⅱc病変で63.5％と最も高い脈管侵襲を示したが，リンパ節転移率は，隆起型が高値を示した．病理組織型の検討では，中分化腺癌群が脈管侵襲を高率に示したがリンパ節転移が存在せず，高分化腺癌群の12.4％にリンパ節転移を認めた．以上より現状における内視鏡治療の適応は，脈管侵襲を伴わないsm_1bまでの病変となるが，今後腫瘍先進部の組織型や分子生物学的アプローチなどの解析を加えることで適応を拡大できる可能性が示唆された．

　Endoscopic polypectomy and mucosal resection (EMR) are very popular and important techniques for colorectal neoplasms, but we must choose between endoscopic therapy or surgical resection in submucosal-invading carcinoma. This study was carried out to clarify the adoption of endoscopic therapy in submucosal-invading carcinoma. During the period from April 1985 to March 1999, we have encountered 328 cases of submucosal-invading carcinoma. In this study, we analyzed 323 cases which could be sufficiently evaluated concerning the degree of submucosal invasion, vessel invasion and lymph node metastasis. The overall rate of vessel invasion in each degree of invasion was sm_1a, 8.3%, sm_1b, 26.7%, sm_1c, 33.3%, sm₂, 70.5%, sm₃, 78.9%. This was 50.8% of the total. The rate of lymph node metastasis in each degree of invasion was : sm_1a and sm_1b, 0%, sm_1b, 0%, sm_1c, 2.9%, sm₂, 11.7%, sm₃, 20.4%. This was 10.9% of the total. There was no lymph node metastasis from the submucosal carcinomas without vessel invasion. We must resect submucosal-invading carcinoma with lymph node metastasis, and estimate that lymph node metastasis has taken place from the fact of vessel invasion. We concluded that endoscopic therapy should be adopted for sm_1a and sm_1b, carcinomas without vessel invasion. In future, there is a possibility that we may overrule this conclusion, but, so far, we have encountered no case of lymph node metastasis in any degree of submucosal invasion without vessel invasion, and we will be able to use molecular biological diagnosis for submucosal carcinomas.