病理組織学からみた大腸腫瘍の自然史

Natural History of Colorectal Carcinoma from a Histopathological Point of View

要旨　どのような肉眼型と組織学的特徴を有するm（粘膜内）癌が進行癌へ進展しやすいかを明らかにするために，m部腫瘍がほぼ完全に保存されているsm癌101病変を用いて検討した．このsm癌の由来肉眼型（m部病変）はⅠp・Ⅰsp型が19.8％，Ⅰs型が36.6％，Ⅱa型が18.8％，Ⅱa＋Ⅱc型が8.4％，Ⅱc＋Ⅱa型が12.9％，Ⅱc型が3.0％であった．進行癌の由来肉眼型もほぼこの割合と推定された．この割合は腺腫，低異型度癌，および高異型度癌の量と高異型度癌の出現時期に大きく左右されると推定された．

　Our study enquired about what kinds of gross type of colorectal intramucosal carcinoma easily develop into advanced carcinoma. For that purpose, we analyzed 101 gross type submucosal carcinomas with the whole tumor contained within the mucosa.

　Intramucosal gross types in these carcinomas were found at the following rate ; Ⅰp・ Ⅰsp (mucosal height＞1 mm) ; 19.8% (20/101), Ⅰs (x＞1 mm) ; 36.6% (37/ 101), Ⅱa(x≦1 mm); 18.8% (19/101), Ⅱa＋Ⅱc; 8.4% (9/101), Ⅱc＋Ⅱa; 12.9% (13/101), and Ⅱc; 3.0% (3/101). Five of the 42 carcinomas of type Ⅰs with the naked eye were classified into type Ⅱa because mucosal height of the tumor is 1 mm or less. Type I carcinoma was associated with adenoma more than type Ⅱ carcinoma, and type Ⅱa tumors with Ⅱc showed a higher frequency of carcinoma with high-grade cytologic atypia than type Ⅰp・Ⅰsp tumors.

　Submucosal carcinoma is reported to be an early phase of advanced carcinoma. Therefore, it is assumed that advanced carcinomas develop at almost the same rate that of intramucosal gross type as these submucosal carcinomas. It is also suggested that intramucosal gross type carcinoma is much influenced by the amount of adenoma, by whether the carcinoma is of low- or high-grade, and by the time when high-grade carcinoma appears.