早期胃癌内視鏡的切除の評価―外科の立場から

Some Considerations on Endoscopic Radical Resection of Early Gastric Cancer

要旨　内視鏡的切除で根治性の得られる早期胃癌をリンパ節転移と多発癌巣の面から検討した．なお，癌巣は内視鏡的に完全に切除しえたものとする．①リンパ節転移のない早期胃癌とは（a）長径10mm未満のすべての肉眼分類の早期胃癌，（b）長径20mm未満の隆起型（Ⅰ，Ⅱa，Ⅰ+Ⅱa）である．②内視鏡的に根治切除可能な胃癌とは早期胃癌であるから，術前の壁深達度診断が肝要である．③早期胃癌，特に内視鏡的切除が適応になる微小胃癌には多発癌巣が高率である．術前の多発癌巣のチェックと術後の厳重なfollow-upを要する．

　In order to accomplish endoscopic radical resection of early gastric cancer, the following requirements have to be satisfied: (1) absence of lymph node metastasis, and (2) complete resection of multiple foci of cancer frequently seen in cases of early gastric cancer. Bearing these in mind, we recently analyzed 482 cases of early gastric cancer treated at our department. The following results were obtained.

　1. Characteristics of early gastric cancer without lymph node metastasis: Lymph nodes were negative for metastasis in cases with the following features: (a) macroscopically tumor size was less than 10 mm in diameter; (b) protruded or elevated type (type Ⅰ, Ⅱa, Ⅰ＋ Ⅱa) with the longest diameter less than 20 mm (Fig. 2).

　2. Diagnosis on the depth of cancer invasion: Because endoscopic radical resection of gastric cancer is feasible only for early gastric cancer, accurate assessment on the depth of cancer invasion preoperatively is mandatory.

　3. Diagnosis on multiple cancer foci: Because early gastric cancer (in particular minute gastric cancer) frequently takes the form of multiple cancers, preoperative detection of these multiple foci is essential to complete resection. After resection, careful follow-up is necessary so as not to overlook local recurrence and residual foci of cancer.