病理形態面からみた大腸癌の発育進展の考え方と問題点

Development of Colorectal Carcinoma Investigated from Pathological Aspects

要旨　これまでの病理形態面からみた大腸癌発育進展経路の考え方には，①粘膜内癌のすべてが進行癌の前段階とは限らない，②肉眼型の判定基準が研究者によって異なる，③sm癌の肉眼型変化様式の推定に組織学的裏付けが乏しい，という問題点がある．こうした問題点を補完し，これまでに提唱された発育進展経路の妥当性を検証するには，粘膜内部が残存するsm以深浸潤癌の組織学的検索が必要である．自験例粘膜内部残存sm癌245例の検討では，大腸癌発育進展経路は，①主に20mm以上のI型粘膜内癌を起点とするものが45％，②主に10mm台のIIa型粘膜内癌を起点とするものが26％，③主に10mm台のIIc型・IIc＋IIa型粘膜内癌を起点とするものが13％，④20～30mm以上の結節集簇様病変を起点とするものが16％であり，②IIa型，③IIc型・IIc＋IIa型粘膜内癌を起点とする癌の一部は，sm浸潤量の増加に伴いその肉眼形態をそれぞれIs型やIIa型・IIa＋IIc型・Is型に変化させると推定される．

　Hypotheses on development of colorectal carcinomas proposed from observing pathological aspects so far, have the following problems ; 1) Not all intramucosal carcinomas are certain to develop into advanced carcinomas, 2) Macroscopic classification differs according to researchers, 3) Speculations on the macroscopic developmental process of submucosal carcinomas are not sufficiently based on histological examination. In order to complement the answers to these problems and confirm the validity of the hypotheses, 245 submucosal carcinomas with remnant intramucosal parts were investigated histologically and the following pathways and possible frequencies were noted ; 1) type I mucosal carcinoma (20's mm) develops to type I submucosal carcinoma (45％), 2) type IIa mucosal carcinoma (10's mm) develops to type IIa, IIa＋IIc, Is submucosal carcinoma (26％), 3) type IIc, IIc＋IIa mucosal carcinoma (around 10 mm) develop to type IIa＋IIc, Is submucosal carcinoma (13％), and 4) nodular aggregated-type mucosal carcinoma (more than 30 mm) resulted in submucosal invasion(16％).