Helicobacter pylori陽性胃癌と陰性胃癌の比較―臨床の立場から

Clinical Feature of Helicobacter pylori-negative Gastric Cancer

要旨　Helicobacter pylori陰性胃癌は全胃癌の約1％を占めるまれな病態である．若年のみならず高齢者にも発生し，比較的女性に多く認められる．肉眼型では平坦陥凹型であることが特徴で，組織学的にはdiffuse typeが相対的に多い．除菌後胃粘膜に生じる胃癌も同様に平坦陥凹型病変として捉えられることが多いが，性別は通常の癌と比較して差を認めず，組織型は陰性癌とは対照的にintestinal typeがほとんどである．除菌治療後早期において，隆起型早期胃癌のうち約1/3は平坦化し指摘困難となる．組織学的には腫瘍表層に異型性の乏しい再生上皮がみられることがあり，この現象が内視鏡診断を困難にしている一因と考えられる．

　Only 1％ of patients with gastric cancer (GCa) were diagnosed as Helicobacter pylori-negative. H. pylori-negative GCa has developed not only in younger but also in elder people, and its prevalence was relatively higher in female than in male. Endoscopically, it appears as a flat depressed tumor and is diagnosed as diffuse type carcinoma histologically. Gastric cancer develops even after eradication therapy and its typical feature is flat depressed cancer with intestinal type appearance. It should be noticed that one third of these tumors become indistinct after eradication therapy especially in cases with flat elevated type GCa. In these tumors, non-atypical regenerative epithelium covers over the tumor and this makes it more difficult to diagnose these tumors.