早期胃癌の範囲診断

Endoscopic Diagnose to Delineate Early Gastric Cancer

要旨●早期胃癌の範囲診断について，H. pyloriの感染状況，胃癌組織型，また内視鏡検査のmodality別，すなわち通常・色素内視鏡（C-WLI & CE），NBI併用拡大内視鏡（ME-NBI）観察の倍率別に範囲診断能について検討した．既報ではH. pylori既感染胃癌では範囲診断が困難とされているが，本検討ではC-WLI & CE観察はH. pylori現感染，既感染にかかわらず同等の診断能であった．ME-NBI弱拡大観察はH. pylori現感染においては最大倍率観察とほぼ同等の正診率を有していたが，H. pylori既感染ではH. pylori現感染の正診率と比較すると有意に低く，ME-NBI最大倍率観察が必要と考えられた．組織型で検討すると，分化型胃癌ではH. pylori感染状況にかかわらず正診率は高かったが，未分化型胃癌は少数例ではあるが各内視鏡modality別での範囲診断正診率は低く，さらにH. pylori現感染においての正診率が低い傾向であった．早期胃癌の範囲診断はH. pylori感染の有無，癌の組織型や内視鏡のmodalityによっても異なり，それらの性質を理解して慎重に行う必要がある．

　We investigated the diagnostic abilities of three endoscopic modalities, C-WLI（conventional white light imaging）, CE（chromoendoscopy）, and ME-NBI（magnifying endoscopy with NBI）, for diagnosing early gastric cancers. The diagnostic abilities of C-WLI and CE for both gastric cancers with HP（Helicobacter pylori）and those without HP were almost same. The diagnostic ability of ME-NBI for gastric cancers with HP was high and constant, regardless of magnification power. However, after HP eradication, the diagnostic ability of ME-NBI with low magnification power was lower than that of ME-NBI with full magnification power. In addition, undifferentiated gastric cancers were more difficult to delineate than differentiated cancers with all the three endoscopic modalities. Therefore, identifying differences in the features of different types of gastric cancers, which undergo various changes due to HP infection, and differences in the diagnostic ability of each endoscopic modality is important.