胃癌EMRの一括切除による根治的切除の判定基準―垂直方向への拡がりからみた検討

Histological Criterion for Complete Resection of Early Gastric Carcinoma Invading the Submucosa: A Special Reference to Submucosal Tumor Invasion and Resected Margin

要旨　内視鏡的胃粘膜切除術(endoscopic mucosal resection；EMR)の材料で粘膜下浸潤を認めた23例のうち，8例ではEMR後に外科的切除術が，1例で追加EMRが施行され，14例では内視鏡的経過観察のみが行われた．外科的切除群のうち，3例には粘膜内(m)および粘膜下層(sm)に腫瘍の残存がみられたが，追加EMR施行例ではmのみに残存，5例では残存腫瘍はなかった．リンパ節転移は1例にのみ認めた．smに残存腫瘍を認めた3例には，非残存例と比較して，①長径が大きく(15mm以上)，②脈管侵襲が明らかであり，③粘膜筋板から500μm以上のsm浸潤を認め，④低分化腺癌成分を含み，⑤切除断端からの距離が200μm以下で，⑥電気焼灼変性を示す例が多くみられた．肉眼的に隆起型を示す腫瘍には，深い浸潤を示す例でも腫瘍残存や再発を認めない例がみられた．上記の臨床病理学的所見を認めないsm癌は，EMRによって治癒的切除の可能性がある．

　We examined 23 early gastric carcinoma cases with submucosal invasion obtained by endoscopical resection (EMR). Eight cases were followed by the additional surgical resection and, in one case, re-EMR therapy was added. In the remaing 14 cases endoscopic follow-up with biopsy examination has been applied. In three cases, residual carcinoma at the submucosal layer as well as at the mucosa was revealed in the surgical specimens. Lymph node metastasis was detected in only one case. The following histological parameters are more frequently observed in the EMR specimens among residual carcinoma cases than among non-residual cases: 1) A large lesion more than 15 mm in diameter. 2) Prominent lymphatic and/or venous invasion. 3) Deep submucosal invasion more than 500μm, beneath the muscularis mucosae. 4) Presence of a poorly-differentiated component. 5) A submucosal invasive front with electrodesiccation artifacts, less than 200μm distant from resected margin. Early gastric carcinoma lacking the above-mentioned histological risky findings could be treated by EMR.