潰瘍の有無からみた早期胃癌のEUS診断

Accuracy of Endoscopic Ultrasonography for Diagnosing the Depth of Early Gastric Cancer with or without Ulcer Fibrosis

要旨　切除胃癌例1,880病変のうち早期胃癌1,133病変を主な対象として超音波内視鏡の深達度診断能の検討を行った．胃癌全体の深達度診断成績は，m癌は91.5％，sm癌は68.7％，mp癌は64.9％，ss癌は74.6％，se癌は83.5％，si癌（非切除例を除く）は61.3％であり，全体では79.6％（1,496/1,880病変）であった．肉眼型別の検討では，パターンによる陥凹型の深達度診断を用いても，Ⅱc＋ⅢおよびⅠ型早期胃癌の成績が通常型超音波内視鏡，細径超音波プローブともに他の群と比較し約10％不良であった．sm亜分類別の検討では，浸潤が1,000μmを超える病変では良好な成績が得られているが，これ以下の微少浸潤例の成績は不良であった．しかしながら，三次元超音波内視鏡の診断能は良好で500μm前後の浸潤まで正診しえており，微少浸潤の問題をある程度解決してくれるものと思われた．

　In this paper, we reported the accuracy of endoscopic ultrasonography (EUS) for diagnosing the cancer depth of gastric cancer, especially early gastric cancer with or without ulcer fibrosis. The accuracy of EUS is 91.5％ in mucosal cancer, 68.7％ in submucosal cancer, 64.9％ in muscularis propria cancer, 74.6％ in subserosal cancer, 83.5％ in serosal cancer, 61.3％ in si (T4) cancer, and totally 79.6% (1,496/1,880). The echo level of ulcer fibrosis is similar to that of cancer, so fibrosis causes wrong diagnosis in gastric cancer with ulcer fibrosis. We proposed pattern analysis for differentiating fibrosis from cancer invasion. Our pattern analysis is based on the fact that, histologically, ulcer fibrosis always has fan-shaped spreading and cancer has arch-shaped spreading.

　However even if we employed this pattern analysis, microinvasion to the submucosa can't be detected by EUS. Therefore, compared to the others, the diagnostic accuracy of EUS in early cancer with ulcer is relatively low.

　However, now, we have three dimensional EUS (3D-EUS) which carries out multiple radial scanning and a linear scan at the same time. Using 3D-EUS, we will be able to detect 500μm invasion to the submucosa in the near future.