狭帯域フィルター（narrow band imaging；NBI）併用拡大内視鏡所見からみた胃分化型SM1癌の診断

Diagnosis of Differentiated-type SM1 Gastric Cancer Using a Narrow Band Imaging System with Magnifying Endoscopy

要旨　SM浸潤が粘膜筋板下端から500μm未満のSM1分化型胃癌には内視鏡治療の適応拡大が試みられており，SM1分化型胃癌の術前深達度診断能の向上が期待されている．目的：狭帯域フィルター併用拡大内視鏡（narrow band imaging system with magnifying endoscopy ; NBI-ME）からみた胃分化型SM1癌の特徴を検討しNBI-MEの深達度診断に対する有用性を検証する．対象：早期胃癌94症例98病変．方法：腺管構造を反映し，分化度と関連していることが証明された"腺管模様"の密度の変化（density change）と破壊像（destructive sign）の有所見率を腫瘍の辺縁と中心部，もしくは粘膜内病変部とSM浸潤部でretrospectiveに比較検討した．結果：density changeはM癌の95％で認められなかった．SM1癌，SM2（500μm以深）癌のそれぞれ86％，67％で認められ，そのうちの67％，75％で密度の低下が観察された．一方，destructive signはM癌では10％，SM1癌では29％に認められるのみであったが，SM2癌では92％に認められた．結語：腺管模様の密度の変化が認められるが破壊されるような強い構造変化がない部分でSM微小浸潤の可能性があることが示唆された．限られた症例での検討ではあるが，NBI-MEは胃分化型SM1癌の診断に有用な可能性があると考えられた．

　Background : According to clinicopathological studies and improvement of endoscopic procedures (ex. endoscopic submucosal dissection ; ESD), early gastric cancers with minute invasion (＜500μm) to the submucosal layer (SM1 gastric cnacer) have become candidates for endoscopic resection. To predict the depth of SM1 gastric cancer is important.

　Objective : To evaluate the efficacy of the narrow band imaging system with magnifying endoscopy (NBI-ME) for predicting the depth of differentiated-type early gastric cancer.

　Materials : A total of 94 patients with 98 early gastric cancers were enrolled in this retrospective study.

　Interventions : All of the tumors were observed and recorded using NBI-ME. We investigated the NBI-ME images, differentiation of the tumor and depth of the tumor invasion.

　Main outcome : Revelation of the prevalence of density change and destructive sign of gland pattern in the tumor.

　Results : The prevalence of density change revealed by the NBI-ME system was lower in intramucosal cancer (5) than in SM1 cancer (86％) and SM2 cancer (67％). The density change had a tendency to be lower in invading lesions. The prevalence of destructive sign was lower in intramucosal cancer (10％) and SM1 cancer (29％) than in SM2 cancer (92).

　Conclusion : The data suggested that minute invasion of the tumor reflects the NBI-ME findings. NBI-ME is efficacious to predict the depth of tumor invasion for selected patients with differentiated-type early gastric cancer.