微小胃癌診断の時代的変遷

Changing Trends in Diagnosis of Minute Gastric Cancers

要旨　1980年代以降，早期胃癌は60歳以上の高齢者に好発するようになり，そのなかでも大きさ30mm未満で，分化型のM癌がおよそ80％を占めるに至っている．さらに，画像強調内視鏡（IEE）が導入された現在では，内視鏡所見のより乏しい，より小さい，より分化度の低い癌が発見できるようになり，5mm以下の微小胃癌を正確にとらえることが可能となった．しかし，IEE導入後に微小胃癌の発見数は増加したが，発見頻度には大きな変化が認められなかったことから，現状のIEEによる微小胃癌のスクリーニングには限界があると考えられる．

　Since the 1980's, EGC（early gastric cancers）occur more often in over 60 years old and it was found that lesions of the size in diameter is less than 30mm, histological type is differentiated, and histological invasion is to the mucosal layer are account for 80％ of EGC. In addition, the introduction of the IEE（image-enhanced endoscopy）enabled us to detect lesions which are smaller and poorer differentiated type such as lacking of endoscopic characteristics, and to diagnose minute gastric lesions qualitatively with more precision. However, we suggested that the introduction of IEE enabled us to detect more minute gastric cancers but, the frequency of detecting them was no significant difference before and after the introduction of IEE. We consider that the present IEE is limited to the screening test of minute gastric cancers.