胃癌側方進展範囲診断―FICE拡大内視鏡による胃癌側方進展範囲診断

Diagnosis of the Extent of Gastric Cancer Using FICE（Flexible Spectral Imaging Color Enhancement）with Magnification

要旨　早期胃癌に対する治療法の進歩により，サイズの大きな病変であっても一括切除が可能となったが，それには正確な範囲診断が必要となる．FICEによる早期胃癌の範囲診断では，非拡大FICE観察で全体像を把握し，弱から中拡大のFICEの近接像で癌部と非癌部の境界診断を行うことが可能である．筆者らの施設ではFICE導入後に側方断端陰性率は93.8％から96.7％に向上した．最新のプロセッサーVP-4450を使用したFICE範囲診断では，側方範囲診断は98.3％であったが，過剰切除も考慮した範囲診断正診率は94.8％であった．20mmより大きい腫瘍径と随伴IIbの存在が有意に範囲診断正診率の低下の原因であった．随伴IIbの正診率は80％と良好であったが，癌の構造異型と背景粘膜との差異が少ない症例や異型度が低い0-IIb症例では，範囲診断を正診できない場合もあることを認識しておかなければならない．

　Early gastric cancers even with large sized diameters have been treated with endoscopic submucosal dissection. An accurate diagnosis of the extent of the tumor is very important for completing en-bloc resection successfully. The FICE system allows us to observe the entire lesion of early gastric cancer without magnification and the demarcation line between the cancerous lesion and the surrounding area with low or half magnification. The prevalence of cases with cancer-free margins in resected specimens improved from 93.8％ without the FICE system to 96.7％with it. Using FICE with the new processor system（VP-4450）, it improved to an extremely high level of 98.3％, but the diagnostic accuracy of cases with appropriately cancer-free margins in the resected specimens, except for cases with broader resection, showed a slightly lower level of 94.8％ because of the misdiagnosis of cases with tumors more than 20mm in diameter or accompanied by a flat lesion. The extent of cancers with 0-IIb could be precisely diagnosed with an accuracy of 80％, but it is difficult to diagnose the extent of cancer in a few cases with no difference of microstructural pattern or with 0-IIb accompanied by highly well-differentiated adenocarcinoma.