胃型・腸型腺癌の特性

Features of Differentiated-type Adenocarcinomas of the Stomach with Intestinal and Gastric Phenotypic Expressions

　胃型と腸型の分化型癌は，臨床病理学的にも分子生物学的にも，大きく異なる特性を有する腫瘍であることが判明しつつある．胃型分化型癌は低分化癌化傾向が高く，これにはE-cadherinの異常の関与が大きい．またhMLH1遺伝子のメチル化とmicrosatellite instabilityが高頻度に生じており，組織発生への関与が示唆されている．生物学的悪性度も通常型の分化型癌に比べて高い．一方，腸型分化型癌には，完全型腸上皮化生形質を強く有し，細胞異型は目立たず構造異型が病理組織診断の決め手となる一群があり，しばしば臨床病理学的に見逃され問題となる．この種の腸型分化型癌もやはり特徴的な臨床病理像を示す．これら胃型および腸型分化型癌の特性について，これまでの報告を踏まえ考察した．

　Differentiated-type adenocarcinomas with a distinct gastric phenotype have quite different clinicopathological features from those with a distinct phenotype of complete-type intestinal metaplasia. The histogenesis is also different between these two groups, as are the genetic and epigenetic changes. Understanding the characteristics of each tumor group is necessary to prevent misdiagnosis of these tumors, which are often difficult to detect both clinically and pathologically. The phenotypic expressions of differentiated-type adenocarcinoma of the stomach are discussed taking clinicopathological and genetic differences into consideration.