未分化型胃癌に対する内視鏡的粘膜切除（EMR）の適応限界―病理の立場から

Limits of Indication of Endoscopic Mucosal Resection (EMR) for Treatment of Early Gastric Carcinoma of Undifferentiated Type-From a Pathological Viewpoint

要旨　未分化型胃癌に対する内視鏡的粘膜切除（EMR）の適応限界を考察するため，外科切除例の未分化型早期胃癌（m癌552例，sm癌233例）を用いて，深達度など諸病理学的事項とリンパ節転移との関係を詳細に分析した．われわれ病理部では，4～8mmの間隔で切り出しを行っているが，m癌およびsm癌のリンパ節転移率はそれぞれ1.8％，21.9％であった．リンパ節転移のない条件は，m癌の場合，①肉眼型が隆起型あるいは平坦型ならば大きさは問わない，②肉眼型が陥凹型であれば，大きさ40mm以下．sm癌の場合，①sm浸潤の深さが200μmまでならば，リンパ管侵襲（ly），潰瘍病変（Ul）の有無は問わない，②sm浸潤の深さが200μmを超える場合は，ly，Ulが陰性であれば，浸潤の深さ900μmまで，あるいは大きさ20mm以下．したがって，従来から，未分化型癌に対する本治療法の適応範囲は，大きさ5mmまでのm癌とされていたが，もう少し拡げてよいと考える．実際的あるいは総合的立場からは，大きさ10mmまで，sm深達度200μmとするのが妥当であろう．

　Limits of indication of endoscopic mucosal resection (EMR) in treatment of early gastric carcinoma of undifferentiated type were considered from a pathological viwpoint, using 785 gastric carcinomas of undifferentiated type (552 mucosal and 233 submucosal carcinomas) surgically resection in CIH. Under a condition where surgical specimens are serially with 4～8 mm thickness, or with a method routinely applied in authors' laboratory, the rates of the case with lymph node metastatis in mucosal and submucosal carcinomas were 1.8% (10/522) and 21.9% (51/233), respectively. Conditions where no lymph node metastasis is expected and, thus, the EMR is possibly effective are as follows. In case of mucosal carcinoma, 1) polypoid or flat tumors with any tumor sizes, and 2) tumors of depressed type with the tumor size 40 mm or less in largest diameter. In case of submucosal carcinoma, 1) tumors with the invasion depth limited to 200 μm from the muscularis mucosae (m.m.) about which any cosideration of lymphatic permeation (1y) and/or ulcerative change (Ul) in the tumor are non-necessary, and 2) tumors with the invasion depth deeper than 200 μm from the m.m., but without any sign of lymphatic permeation and/or ulcerative change, and further with either or both of the following conditions, the invasion depth up to 900 μm and the tumor size up to 20 mm.

　Therefore, the EMR indication hitherto adopted in treatment of gastric carcinomas of undifferentiated type, i.e., the mucosal carcinomas up to 5 mm in diameter, can be made wider. However, from a practical view point considering particularly a general tendency of tumors to make submucosal invasion with the size, the tumor size up to 10 mm and the submucosal invation up to 200 μm from the m.m. would be the most reasonable congitions in applying the EMR procedure for treatment of gastric carcinomas of undifferentiated type. It is, of course, essential in this treatment to examine the specimens stepwise and to check carefully their cut-ends and the grade of submucosal invasion.