表在型食道扁平上皮癌の内視鏡診断と治療の進歩―黎明期から現在まで

Progress of Endoscopic Diagnosis and Treatment for Superficial Esophageal Squamous Cell Carcinoma

要旨

ヨード液を用いる色素内視鏡により1980年代には表在性食道癌が多数発見されるようになり，外科的切除で根治が得られた。しかし，合併症リスクや臓器脱落症状は避けがたく，臨床病理学的にも過大な侵襲が問題であった。そのため，内視鏡切除術を安全容易に行うべくさまざまな工夫がなされEMRが広く普及した。さらに食道ESDの手技が確立すると適応拡大への期待が高まった。同時にEMR・ESDの適応判断に精密な深達度診断が必須であると認識され，食道壁構造を描出する内視鏡的超音波診断，表層微細血管の状況から腫瘍伸展を推定する画像強調拡大観察の検討も進んだ。表在型食道癌に対するESDは技術的な制約をほぼ克服したが，転移診断に本質的な壁が残る。技術の習得や新技術の開発というハード面だけではなく，既存技術の柔軟な活用というソフト面での進歩が表在型食道癌診療のレベルをさらに高めつつある。

　Many flat esophageal superficial cancers have been detected since the 1980s by chromoendoscopy using iodine solution, and surgical resection has made it possible to obtain definite cure of cancer. However, risks of complication and the appearance of organ dropout symptoms are inevitable, and from the clinicopathological viewpoint, a cure obtained by excessive invasion is a problem. For this reason, various techniques were devised to perform endoscopic resection safely and easily in the esophagus, and esophageal EMR became popular. Furthermore, the expectation for expansion of adaptation of endoscopic resection has increased as the esophageal ESD procedure was established. In addition, it is recognized that precise diagnosis of depth of tumor invasion is indispensable for EMR/ESD adaptation judgment, so ultrasonic diagnosis by high-frequency thin probe and magnified image enhanced endoscopy have been actively used for diagnosis of depth of tumor invasion. With regard to extended indication of endoscopic resection, ESD has largely solved the technical constraints, but there is still a big barrier to metastasis diagnosis. In addition to the hardware development, a breakthrough from the viewpoint of software in how to combine established technologies is ongoing.