食道表在癌の深達度診断―超音波内視鏡の立場から

Endoscopic Ultrasonography for Patients with Esophageal Cancer

要旨　食道表在癌の治療は多様化し，患者背景や希望をより重視して治療法を選択するようになってきた．そのため，治療方針決定のうえからT1a-LPM，T1a-MM，SM1，SM2などの見極めが特に重要となっている．細径プローブを用いた超音波内視鏡は，腫瘍の壁内進展状況を詳細な断層画像として表すことができる唯一の実用段階の検査法である．通常内視鏡による表面形態や色調，拡大内視鏡による微細血管の変化などの所見と照らし合わせ，総合的に診断するが，良好な超音波像を得，それから固有筋層，粘膜下層を同定すれば，深達度診断は比較的容易である．しかし，超音波像にはリンパ組織の増生や拡張した固有食道腺など腫瘍以外の様々な変化が表現されるため，それらを常に考慮することも重要である．

　The most appropriate treatment modality for a patient with superficial esophageal cancer is decided by the patient himself or herself according to each patient's background. In this situation, precise and accurate diagnosis of depth of tumor invasion, e. g. differentiation between T1a-LPM, T1a-MM, SM1 and SM2, has been becoming more and more important. The most objective information about tumor invasion is obtained by enodoscopic ultrasonography using a high frequency ultrasound thin probe in patients with superficial esophageal cancer if clear images can be obtained. Ultrasound layers of the proper muscle and submucosa are very important for showing precise information of tumor invasion, and we can easily provide a clinical diagnosis of tumor invasion by fine ultrasound figures with supportive information of conventional endoscopy images and capillary changes in magnifying endoscopy. However, various factors included in ultrasound figures such as lymphoid hyperplasia and an enlarged proper esophageal gland should always be considered.