大腸T1癌の内視鏡診断変遷―SM1（200～300μm）からT1a（＜1,000μm）への診断学

Endoscopic diagnosis of T1 colorectal cancer: transition from “SM1”（200-300μm）to T1a（＜1,000μm）

要旨

大腸T1癌の内視鏡診断は，大腸癌取扱い規約におけるSM浸潤の評価の変化とともに発展してきた。SM浸潤におけるいわゆる相対分類に対する診断能，sm2～3をsm massiveとした場合の診断能などが検討されてきた。その後大腸T1癌はT1aとT1bに分けられ，T1bは，200～300μmから，1,000μm以深へと改訂され，通常光，クリスタルバイオレット拡大観察/pit pattern診断，超拡大内視鏡/EC分類やartificial intelligence（AI）を用いた検討まで，T1bの診断に対するさまざまな検討がなされてきている。大腸SM癌の診断基準の時代的変遷と，現在のSM1,000μm以深の診断学について，通常光・拡大観察・超拡大観察・AIについて総説する。

　The endoscopic depth diagnosis of colorectal T1 cancer has evolved along with changes in the evaluation of SM invasion in the colorectal cancer guidelines. The diagnostic performance of the so-called relative classification of SM invasion and the diagnostic performance of sm2-3 as sm massive have been studied by many endoscopists. After colorectal T1 cancer was defined as T1a and T1b, various studies have been conducted for the diagnosis of T1b. Conventional white-light imaging, crystal violet staining magnification, pit pattern diagnosis, NBI magnification, endocytoscopy (EC classification), as well as artificial intelligence (AI) have been evaluated in various studies. We review the evolution of diagnostic criteria for colorectal SM cancer over time and the current diagnostic science for SM deeper than 1,000μm with respect to normal light, magnification, ultra-expansion, and AI.