食道胃接合部腺癌のリンパ節転移頻度と特徴─多施設共同研究の結果から

The Clinicopathological Characteristics and Prevalence of Superficial Esophagogastric Junctional Adenocarcinomas with Lymph Node Metastases

要旨●食道胃接合部腺癌の転移頻度や特徴は明らかではなく，内視鏡的切除の治癒判定が確立されていなかった．特にSM1を食道癌・胃癌どちらに準ずるべきか課題となっていた．われわれは食道腺癌の転移リスクを明らかにするため多施設共同研究を行い，今回その結果の中から食道胃接合部腺癌のみを抽出し解析を行った．外科的切除もしくは内視鏡的切除を行った粘膜癌，粘膜下層癌385例中54例に転移を認めた．深達度別では深層粘膜筋板浸潤癌では6.9％（6/87）に転移を認め，SM 500μmまでに浸潤した癌では3.9％（2/51）に転移を認めたが，病変径30mm以下で脈管侵襲，深層粘膜筋板以深の低分化腺癌成分を持たないものに限ると転移は認めなかった．この結果より食道胃接合部腺癌におけるSM1は500μmまでとするのが妥当と考えられた．

　The criteria of curative endoscopic resection have not been well-established yet because little is known about the characteristics and prevalence of lymph node metastases in superficial esophagogastic junctional adenocarcinomas, especially, the discussion of whether SM1 invasion should be defined by the criteria of esophageal cancer or gastric cancer. Accordingly, we conducted a multicenter retrospective study in order to elucidate the risks of metastasis in adenocarcinoma of the esophagus, and patients with esophagogastric junctional adenocarcinomas were selected in this study. Among 385 patients who were subjected to surgery or endoscopic resection for mucosal or submucosal adenocarcinoma of the esophagogastric junction, 54 patients were diagnosed with metastatic cancer. With regards to the invasion depth, metastasis was observed in 6.9％（6 out of 87）of the patients with the cancer invading into the deeper muscularis mucosa and in 3.9％（2 out of 51）of the patients with SM cancers invading less than 500μm from the muscularis mucosa. In the latter cases, no metastasis was observed in the patients without factors such as lymphovascular involvement, poorly differentiated component, and lesion size <30mm in diameter. Thus, we conclude that the depth of SM1 invasion should be defined as less than 500μm from the muscularis mucosa.