進行胃癌の治療方針update—外科医の立場から

Treatment Strategy for Advanced Gastric Cancer：From the Surgeon's Standpoint

要旨●局所進行胃癌に対しては手術先行＋術後補助化学療法が日本の標準治療であるが，高度リンパ節転移症例では術前化学療法が選択される．限局型では30mm，浸潤型では50mmの肉眼的マージンを保ち，D2郭清を伴う幽門側胃切除か胃全摘を行う．食道胃接合部癌では噴門側胃切除を選択する場合が多いが，手術アプローチを決定する際に，食道側と胃側の浸潤距離の術前評価が重要となる．大彎浸潤を来した胃上部進行胃癌では脾門郭清が必要となる．幽門側胃切除に関しては，進行胃癌であっても腹腔鏡下手術が標準治療とされている．切除可能境界胃癌では化学療法後の手術を前提とした集学的治療を行う．切除不能胃癌に対しては化学療法が第一選択であるが，ダウンステージしR0切除が可能と判断された場合，コンバージョン手術を行う場合もある．

　In Japan, the standard treatment for locally advanced gastric cancer is surgery followed by adjuvant chemotherapy ; however, preoperative chemotherapy is preferred during extensive nodal metastasis. Distal or total gastrectomy with D2 dissection is performed with a gross margin of 30mm in localized cases and 50mm in invasive cases. Proximal gastrectomy is often preferred for esophagogastric junction cancer, but preoperative evaluation of the distance between the esophageal and gastric invasion is vital for deciding on the surgical approach. Splenic hilar dissection is necessary for advanced proximal gastric cancer with invasions involving a greater curvature. The standard of care for distal gastrectomy, including advanced gastric cancer, is laparoscopic surgery. For borderline resectable gastric cancer, the prerequisite for multidisciplinary treatment is chemotherapy followed by surgery. Chemotherapy is the first-line treatment for unresectable gastric cancer, but conversion surgery is an option for downstaged cancer if R0 resection is deemed possible.