深達度診断からみた側方発育型大腸腫瘍（LST）の分類と意義―内視鏡診断の立場から：通常観察からみたLSTの深達度診断

Laterally Spreading Tumor ; LST─Classification and Significance : the Diagnosis of Depth of Invasion in Laterally Spreading Tumor（LST）by Conventional Endoscopy

要旨　LSTをLST-G-H，LST-G-MとLST-NG-FE，LST-NG-PDに分類し，臨床的背景，大きさと病理組織の関係，および通常内視鏡観察におけるSM深部浸潤癌の指標について検討した．LST-Gは盲腸と直腸に多く，LST-NGは横行結腸に多く存在し，LST-GはLST-NGに比して有意に大きかった．LST-Gは腫瘍径が大きくなるに従い担癌率が上昇し，LST-NGは小さい病変においても担癌率が高く，深部浸潤率も高値であった．通常観察における深達度診断の指標としては緊満感を伴う二段隆起または陥凹内隆起が重要であった．

　We retrospectively analyzed the epidemiological data of the laterally spreading tumor（LST）, which was divided macroscopically into the following subtypes ; LST-G-H, LST-G-M, LST-NG-FE and LST-NG-PD, and investigated the relationship between the size of the tumor and the histopathological findings of these lesions, and investigated macroscopic findings of the invasive cancer.

　LST-G was more frequently located in the cecum and rectum than LST-NG, and the larger the size of the lesion, the higher the rate of early cancer in LST-G. On the other hand, LST-NG was smaller and located more frequently in the transverse colon than LST-G, and the rate of invasive cancer was higher than that of LST-G.

　According to our investigation of macroscopic findings of invasive cancer, lesions which have an elevation with swelling are highly indicative of invasive cancer, and are thus very important signs for diagnosis of invasive cancer.