| [ Summary ] |
In 1986 colonic depressed lesions (Type IIc) were first identified by Kudo et al. Laterally spreading tumors of the non-granular type (LST-NG) were first identified in 1990 as IIc-like lesions. These lesions have come to be as well recognized globally as IIc lesions. LSTs are now classified into the LST granular type (LST-G) which are thought to arise from the "adenoma-carcinoma sequence" and the LST-NG type as IIc-like lesions which are thought to arise de novo. Therapeutically, "en bloc" endoscopic submucosal dissection (ESD) is indicated for the latter, while "piecemeal" endoscopic mucosal resection (EMR) is also indicated for the former. As with colonic IIc lesions, LST-NG lesions are often difficult to identify and have come to be positioned as the most important of all interval cancers, as observed in the Japan Polyp Study (JPS). LST-NGs are expected to lend themselves more readily to accurate diagnosis in the years to come with advances in endoscopic imaging such as en hanced imaging. It remains our current and future mission, as Japanese endoscopists, to contribute to further elucidation of LSTs by conducting wideranging research using "en bloc" specimens obtained with ESD or magnifying endoscopy-based detailed observation of LSTs as they develop, and progress to malignancy. |