除菌後発見早期胃癌における拡大観察の有用性と限界

Usefulness and Limitation of Magnifying Endoscopy for Diagnosing Early Gastric Cancer Detected after H. pylori Eradication

要旨●当院でESDを施行した2cm以内のH. pylori既感染胃の早期癌48症例54病変を検討した．NBI非拡大観察の病変内の色調（茶色：同色：白色：緑色）は病変外と比較し48：2：2：2例であった．またNBI拡大観察で厳密な境界を引ける境界明瞭群は88.9%であった．一括完全切除率は100%で，マーキング外に病変が進展した症例はなかった．境界明瞭群・不明瞭群で比較すると癌の細胞異型度，表層非腫瘍上皮の程度などに差はなかった．また表層非腫瘍上皮の程度は癌の異型度で差はなく，背景粘膜とも相関はなかった．NBI拡大像から表層非腫瘍上皮の存在・程度を推測することは困難だった．NBI拡大観察時のほうが範囲診断しづらい場合もあり，白色光観察およびNBI非拡大観察での全体像の把握も大切である．

　We evaluated 54 cases of early gastric cancers of tumor size <2cm detected in 48 patients with a history of successful Helicobacter pylori eradication or in those diagnosed with spontaneous eradication. The tumors appeared brownish, the same color, whitish, and greenish in color in 48, 2, 2, and 2 lesions, respectively, as compared with the color of the surrounding mucosa. The borderlines of approximately 90% of the lesions were accurately delineated using low-power magnification endoscopy with narrow-band imaging（NBI-ME）. The en bloc resection rate was 100%, and cancer had not spread beyond the marking dots. No difference was noted in the degree of cytological dysplasia of the cancers and in the extension of surface NE（non-neoplastic epithelium）between the lesions with distinct and indistinct borderline. In addition, the degree of NE was unrelated to the cytological dysplasia and the condition of the surrounding mucosa. It was impossible to predict the existence and the degree of NE by examining the NBI-ME findings. NBI-ME did not always show clearer borderline than white light imaging, whereas NBI without magnification did show clear borders; therefore, observing a wider area beyond the lesions with white light imaging of the entire area is also important.