早期胃癌に対する内視鏡的切除の適応拡大―未分化型腺癌について

Expanded Indication for Endoscopic Resection From the Pathological Viewpoint―The Possibility of sm Invasion by Undifferentiated-type Early Gastric Cancer

要旨　外科切除された未分化型早期胃癌534例より未分化型腺癌に対する内視鏡的切除の適応を検討した．リンパ節転移は，深達度SM，ly・vあり，30mm以上，porあるいはpor＋sig，Ki-67局在なし，二層構造（MUC5AC/MUC6）なしで多かった．SM浸潤率は，porあるいはpor＋sig，Ki-67局在なし，二層構造なしで高かった．M癌のみではUL（＋）でリンパ節転移が多かった．M癌でリンパ節転移を認めた15例中14例でULを認めた．ULなしの1例は，長径80mm，粘膜全層性，Ki-67局在なし，二層構造なしの症例だった．以上よりM癌で①ULの有無を問わずに大きさ10mm以下，②UL（－）かつKi-67局在あり，③UL（－）かつMUC5AC/MUC6二層構造あり，④UL（－）かつsigのみ，がリンパ節転移のない条件と考えられた．

　Expanded indication for endoscopic resection in treatment of early gastric carcinoma of undifferentiated-type was considered, using 534 cases of gastric carcinomas of undifferentiated-type surgically resected from 1994 to 2001 in NCCH.

　We examined the relationships between clinicopathological features and ① the rate of lymph node metastasis, ② the possibility of sm invasion, ③ cases of lymph node metastasis from intramucosal cancer. By univariate analysis, there were statistically significant differences between lymph node metastasis and depth (sm), the presence of lymphatic involvement and venous involvement, the size of cancer (over 30 mm), histology (except for signet ring cell carcinoma), the absence of Ki-67 localization, and the absence of double layer (MUC5AC/MUC6). There were statistically significant differences between sm invasion and histology (except for signet ring cell carcinoma), positive of MUC2, negative of MUC6, the absence of Ki-67 localization, and the absence of double layer (MUC5AC/MUC6). There was statistically significant difference between lymph node metastasis and the presence of ulceration in intramucosal lesions. 14 of 15 cases that had lymph node metastasis in intramucosal lesions had ulceration. One case without ulceration was 80 mm in its largest diameter, invasion depth of the whole mucosal layer, the absence of Ki-67 localization, and the absence of double layer (MUC5AC/MUC6). Therefore, conditions where no lymph node metastasis is expected and thus where endoscopic resection is possibly effective are as follows. In case of mucosal carcinoma, ( 1 )the tumor size 10 mm or less in largest diameter, ( 2 )the presence of Ki-67 localization without ulceration, ( 3 )the presence of double layer (MUC5AC/MUC6) without ulceration, and ( 4 )only signet ring cell carcinoma without ulceration.