胃癌の形態学的変遷―特に早期診断の進歩を中心として

Morphological Changes of Gastric Cancer: Progress in Early Detection

要旨　東京都がん検診センター外来で，18年間（1972～1989年）のうちに発見された胃癌の形態学的変遷と，50歳以上の性・年齢別構成の等しい健康人中から発見された胃癌について，12年間（1978～1989年）の形態学的変遷について考察し，次のような結果を得た．①外来発見癌については，Ⅰ型，およびⅠ型を含む早期癌の減少，Ⅱa型早期癌の増加，10mm以下の小胃癌の増加，Ⅱc類似進行癌の増加，Borrmann4(LPを含む)の増加などである．これらの変貌は早期胃癌の増加など診断の進歩による見かけ上の変化によるものが多い．②健康人中に存在する胃癌については，a)Borrmann4(LPを含む)を含む低分化型癌の増加，12年間の胃癌の罹患率に変化はない，b)Ⅱc類似進行癌の減少，である．a)は本質的な変化で，b)は見かけ上の変化と考えられる．多発早期胃癌は，発見された早期胃癌の12.5％と高頻度に認められ，粘膜切除術の施行に際し，今後十分に検討すべき課題である．

　We analyzed morphological changes of gastric cancer in the two groups: one group was ambulatory patients of The Tokyo Metropolitan Cancer Detection Center during the period between 1972 and 1989, and the other group was asymptomatic healthy people older than 50 year old, which was matched with the former group for age and sex, during the period between 1978 and 1989. The morphological changes of gastric cancer for 18 years in the ambulatory group were as follows: 1) type Ⅰ early cancers decreased; 2) type Ⅱa early cancers increased; 3) gastric cancers of small size increased; 4) type Ⅱc mimicking advanced gastric cancers increased; 5) Borrmann type 4 including linitis plastica (LP) type advanced cancers increased. These changes may be due to a relative increase in early cancers with the progress in detection of early diseases. The changes of gastric cancer for 12 years in asymptomatic healthy people were as follows: 1) poorly differentiated cancers including Borrmann type 4 and LP type advanced cancers increased, and the incidence of gastric cancers remained the same; 2) type Ⅱc mimicking advanced cancers decreased. The former result seems to be due to essential changes but the latter may be due to relative changes. Multi-centered early gastric cancers were quite common at 12.5% of early gastric cancers. We should consider mufti-centered occurrence when choosing gastric mucosal resection as a treatment.