大腸癌：表面型早期癌から進行癌へ―水平発育型腫瘍の提唱

Colon Cancer : Growth from Superficial Early Cancer into Advanced Cancer, Proposal of the Concept of Horizontal Growing Tumor

要旨　表面型早期癌と進行癌の関係は興味あるところだが，これまで両者をつなぐ手掛かりがなく，推測の域を出なかった．表面型腫瘍（FN）を形態と組織の両面から定義し，その組織学的定義に合致する所見（残存した粘膜内に水平発育型癌を認める）が表面型以外の形態をとるsm以上の深達度の癌に認められたとき，その癌は最初は表面型であったと考えることができる．そのような判定基準でsm癌，mp癌，ss以上の癌について表面型起源率をみたところ，sm癌29.4％，mp癌7.1％，ss以上の癌2.3％であった．mp以上の深達度の癌では粘膜の癌が消失しているので，実態を反映していない．sm癌の値が現段階の検索方法で得られる最も妥当な数値と考えられる．FNの本質は水平発育であることから，将来は表面型という概念（形態的要素）を取り払って水平発育型という概念（組織像）のみで定義することを提唱した．

　The relationship between superficial early cancer and advanced cancer is interesting, however, there has been no evidence but speculations to demonstrate it. We designated superficial type tumors from the both morphological and histological viewpoints. Histological designation of superficial type tumor was that there was horizontal growth of cancer in the residual mucosa. Those cancers with the following features were regarded arising from superficial type tumors : 1) Invasion was deeper than the sm layer, 2) Their macroscopic shape was other than superficial type, and 3) Histological examination showed horizontal growth of cancer in the mucosa. The rates of arise from superficial tumor in each groups of depth of invasion were as follows : submucosal cancer ; 29.4%, muscularis propria cancer ; 7.1%, cancer with invasion deeper than the subserosa layer ; 2.3%. The cancer with invasion deeper than the muscularis propria layer usually loose cancer in the mucosa, therefore, the rates may not reflect actual incidence. The rate of submucosal cancer may be close to the actual rate at present. It may be useful to focus on the horizontal growing tumor of the colon for understanding the advance and development of colon tumors. At present horizontal growth would be considered in addition to flat neoplasm (FN), however, the essence of FN is horizontal growth, therefore, we strongly suggest that superficial tumor should be designated only by horizontal extension without FN.