表層拡大型早期胃癌と進行癌のつながり

Relationship between Superficial Spreading Type Early Gastric Cancer and its Advanced Form

要旨　1962年の当センター開設以来，1991年12月までに外科的に切除された胃癌7,398例中，m癌1,178例，sm癌974例，mp癌506例を腫瘍最大径によって25mm以下，26～50mm，51～75mm，76mm以上と4群に分け，各群の臨床病理像を比較検討した．最大径が51mm以上の早期胃癌を表層拡大（表拡）型早期癌と定義すると，それは全早期癌の15％を占め，その頻度は年々漸減していた．表拡型早期癌では，男女比が1.5と低く（早期癌2.5），M領域に多く，signet-ring cell carcinomaが多いことが特徴であり，76mm以上のmp癌も同様の性状を有していることから，両者間の強い結び付きが推定された．76mm以上のmp癌は，50mm以下のmp癌と比べてmp層への腫瘍浸潤範囲が狭く，38％が内視鏡的にもⅡcまたはⅡc類似進行癌と診断され，癌細胞が粘膜面を広範囲に拡がった後，少しずつ垂直方向へと浸潤してゆくと思われる．更に，表拡型早期癌はapoptosisが盛んで，血管新生因子b-FGFの発現に乏しく，このような生物学的性質が癌細胞の粘膜内進展に関与しているのかもしれない．

　One thousand one hundred and seventy-eight mucosal cancers, 974 Submucosal cancers, and 506 muscularis mucosae (mp) cancers of the stomach, which were surgically resected at NCCH between 1962 and 1991, were respectively subdivided into four groups according to the maximum diameter of tumor (A: 25 mm≧, B: 26～50, C: 51～75, and D: 76 mm≦). We defined superfical speading type as an early cancer with a diameter over 51 mm, and speculated its advanced form by comparison of the clinico-pathological features in the subdivided groups.

　Sex ratio and location in the stomach of superfical spreading type cancers were almost similar to those of mp cancer exceeding 76 mm. These findings suggested that the advanced form of superfical spreading type would be mp cancer over 76 mm.

　Pathologically, in mp cancer over 76 mm in diameter, quantity of mp invasion was small, compared with its mucosal spreading area. This pathological featue would contribute to form characteristic endoscopic findings such as Ⅱc-like advanced cancer.