胃癌縮小手術後の異時性胃癌

Gastric Carcinoma Following Function-preserving Limited Gastrectomy for Early Gastric Cancer

要旨　縮小手術はendoscopic mucosal resection（EMR）と並んで，早期胃癌治療法の選択肢のひとつである．理論上胃切除術の残胃粘膜面積が広ければ，それだけ胃機能が温存される利点の反面，異時性胃癌の発生リスクは高まる．機能温存縮小手術160例の1～12年（中央値5.2年）の追跡で異時性胃癌は5例発見され，術後5年での頻度は2.8％であった．この頻度は，報告されているEMRのそれより低く，幽門側胃切除術のそれと同等であった．Helicobacter pylori（HP）感染は術前ではほぼ全例に認められたが，機能温存縮小手術により約半数まで減少し，5年以降に再度上昇する傾向がみられた．HP有病率低下の原因は不明であるが，迷走神経切離による急激な胃内部環境の変化が考えられた．観察された異時性胃癌5例のうち2例は，術後いったん陰性化したHP感染が発見時には陽性となっていた．進行度は4例が早期，1例が進行で，2例は幽門側胃切除術，2例はEMRで再発を認めていないが，スキルス胃癌症例は死亡した．

　A function-preserving limited gastrectomy (FPLG), as well as endoscopic mucosal resection (EMR), is an option among treatment modalities for early gastric cancer with no nodal involvement. However, FPLG carries the risk of metachronous gastric cancer. The wider the mucosal surface of residual stomach after surgery is, the higher the risk of carcinogenesis. Since 1995, 160 early gastric cancer patients with sentinel nodes negative received FPLG, which consisted of local resection, segmental gastrectomy, proximal gastrectomy and limited distal gastrectomy. Of these 160 patients, 5 patients developed metachronous gastric cancer. The incidence of metachronous gastric cancer at 5 years after surgery was 2.8％, which was less than that that for EMR and almost the same as that for conventional D 2 distal gastrectomy. Helicobacter pylori (HP) infection was recognized in almost all patients before surgery and in approximately half of them after surgery. The HP eradication might be associated with alteration of the gastric internal milieu, which was induced by vagotomy combined with lymphatic basin dissection along the lesser curvature. Of the 5 patients with metachronous gastric carcinoma following FPLG, 4 were diagnosed at an early stage, and one was diagnosed at an advaced stage. Two patients were treated with EMR and 3 with gastric resection using laparotomy. Four patients lived without recurrence, but one died because of recurrence.