大腸sm癌の細分類（浸潤度分類）とその問題点

Histological Classifications of Submucosal Invasion of Colorectal Carcinomas-Their Review and Problems

要旨　大腸sm癌の浸潤度分類の概要を述べ，その問題点について検討，考察した．現行のsm癌浸潤度分類は，相対値による分類，sm浸潤量絶対値による分類，sm深達レベルによる分類に大別される．相対値による分類と，sm浸潤量絶対値による分類には，浸潤度判定の基準線の規定に問題があり，その客観性（再現性）の向上のためには，粘膜内癌部とsm浸潤部の判定を明確かつ具体的に行う必要がある．また，相対値による分類には，肉眼型や病変の大きさにより，同じsm浸潤量でも浸潤度判定が異なるという問題がある．各浸潤度分類間でリンパ節転移との相関性，リンパ節転移リスクに対する絶対安全領域の設定，について比較検討した結果，sm浸潤量絶対値に基づく浸潤度分類が，内視鏡的摘除大腸sm癌の追加腸切除適応を決めるうえで最も有用な分類であると考えられた．

　Histological classifications of submucosal invasion of colorectal carcinomas were reviewed and their problems were discussed. The present classifications were divided into three categories: (1) classification by relative value (Kudo'sclassification) or (2) classification by absolute value (Okabe's classification) of the amount of submucosal invasion, and (3) classification by the level of the submucosal invasion (Haggitt's classification). Both Kudo's and Okabe's classification had a problem with objective (or reproducible) judgement of the degree of submucosal invasion by the carcinoma. The former especially had a problem in that its judgment of the degree of submucosal invasion was influenced by macroscopic type and size of the lesions. Investigating the correlation with lymph nodal metastasis among the three classifications, the one based on the absolute value of the submucosal invasion is regarded as the most useful classification to decide what further additional surgery should be undertaken after endoscopic resection.