ESD治療の困難な病変の臨床的特徴と対策

Clinical Characteristics of Gastric Cancers That Are Difficult to Treat by Endoscopic Submucosal Dissection and Measures Against Them

要旨●JCOG0607において，潰瘍を有しない〔以下，UL（−）〕2cmを超えるcT1a分化型癌，および潰瘍を合併〔以下，UL（＋）〕する3cm以下のcT1a分化型癌に対する胃内視鏡的粘膜下層剝離術（ESD）の有効性と安全性が示され，同病変が2018年の「胃癌治療ガイドライン」の改訂で絶対適応病変に変更された．適応が拡大することで，技術的にESDが難しい症例が増えることが予想される．ESDの治療困難因子について検討したJCOG0607の副次解析では，UL（−）かつ>3cm，局在がUまたはM領域，60歳以下が治療困難因子として挙げられた．牽引法などの治療の工夫や技術の進歩，処置具などの治療機器の開発により，ESDの治療困難性は徐々に解決してきていると思われる．これからもわれわれは，ESDをより安全な治療法とするために，治療困難性に影響する因子をしっかりと理解したうえで，新しい処置具や治療方法を開発していく努力を続ける必要がある．

　In the JCOG0607 clinical trial on expanded indications for endoscopic submucosal dissection（ESD）, patients with ulcer（UL）-negative tumors >2cm or UL-positive tumors ≤3cm in size showed equivalent survival to those who underwent surgery with lymph node dissection. Thus, the clinical guidelines published by the Japanese Gastric Cancer Association in 2018 were expanded for ESD indications to include T1a intestinal-type gastric adenocarcinoma with UL-negative tumors >2cm or UL-positive tumors ≤3cm in size. These expanded indications can be problematic, resulting in issues like longer procedure time（≤120min）, perforation, and/or piecemeal resection. Using the data from JCOG0607 to explore the factors related to technical difficulty of performing ESD for early gastric cancer, we found an association with UL-negative tumors >3cm in size, tumors located in the upper- or middle-third portion of the stomach, and patients ≤60 years old. Innovative methods, such as the use of traction apparatus and improvements in cutting devices, have gradually resolved the technical difficulty of ESD. Therefore, continuous efforts are necessary to develop new methods and devices for safer execution of ESD.