胃癌治療の現況と将来―内視鏡治療

The History of Endoscopic Treatment of the Gastric Cancer―From Polypectomy to ESD

要旨　胃癌の内視鏡治療はポリペクトミーで始まった．しかし，胃癌の大部分を占める平坦陥凹型癌にはスネアリングが不可能であった．そこで，レーザー等の破壊法が開発された．しかし，破壊法では病理学的確証が得られない．平坦陥凹型への挑戦が始まった．様々な努力が積み重ねられ EMR（endoscopic mucosal resection）時代には平坦陥凹型癌をも内視鏡的に切除できるようになった．だが，一括切除率は低く，局所再発率が高かった．大きく・正確に切除できる新たな治療法が必要であった．様々なend knivesが開発されESD（endoscopic submucosal dissection）が確立された．ESD時代の今，内視鏡医は任意の範囲を切除できるようになった．こうなると側方進展範囲の診断が重要な意味を持つようになる．診断と治療は内視鏡医の両輪である．内視鏡医の新たな挑戦は今日も続いている．

　Endoscopic resection for gastric cancer was derived from polypectomy in 1968, but only protruded lesions could be resected by the polypectomy method. So a kind of destruction method with laser irradiation was developed to treat flat lesions. The EHRSE method developed by Hirao in 1993 and the strip biopsy (SB) method developed by Tada in 1994 made it possible to resect flat lesions. The SB method became popular because it was easier than ERHSE to use.

　The aspiration methods (EMRC, EAM etc.) were developed in the 1980s and these techniques were called EMR (endoscopic mucosal resection). In the EMR generation, even depressed lesions became resectable. However, the size of resectable lesions was only 15～20 mm and precise resection was impossible. The local recurrence rate of piecemeal-resected cases was higher than that of one-piece-resected lesions. From this, it is obvious that a new method that can cope accurately with larger lesions was desirable.

　Hosokawa developed the IT knife to improve the safety of the needle knife. Oyama developed the Hook knife to resect submucosal fibers directly. Yamamoto used sodium hyaluronate as a submucosal injection medium to keep the lesion elevated longer than saline is able to. After that, Yahagi used fine snare instead of needle knife to improve the safety of the needle knife. Finally, a new endoscopic resection method, endoscopic submucosal dissection (ESD), with end knives was developed. A precise large resection was able to be performed by ESD. One-piece-resection rate was improved by this new technique. However, there remain certain problems, the training system, complications and so on. Endoscopic surgery is challenged to develop a new technique that will enable perfect resection of lesions.