胃癌肉眼分類の問題点―5型胃癌を中心に

Issues on the Gross Classification of Gastric Cancer, Focusing on Type 5

要旨　（1）教室の肉眼分類5型癌を，①早期癌を過大診断したもの，②早期癌と過小診断したもの，③いわゆる早期癌類似進行癌，④分類不能型，の4型に分け検討した．（2）過大診断群と過小診断群はいずれも組織診断の結果判明したものであり，肉眼分類に組織診断介入の可否は今後検討されねばならないが，私見としては肉眼所見による分類に徹すべきと思う．（3）過大診断群，過小診断群，分類不能型の術後生存率をみると，前2者は早期胃癌と同程度の5生率を示すが，分類不能型の5生率は低い．（4）従来5型と分類されたなかには進行癌分類で表現しうるものもあるので，これは5型から脱して分類するように検討したい．（5）そのためには従来のBorrmann分類を見直し，癌巣の形状，進展様式を端的に表す表現法を設定することが必要である．

　1. Gross classification type 5 gastric cancers experienced at our department were analysed and devided into four groups; 1) early gastric cancer overestimated as advanced cancer, 2) advanced cancer underestimated as early cancer, 3) so-called advanced cancer simulating early cancer, and 4) cancer unclassified macroscopically.

　2. The overestimation or underestimation in groups 1) and 2) were corrected by histopathological review, which suggested that the appropriateness of histopathological intervention in gross classification remains to be discussed in the future. The author would like to propose that the classification should be based on gross findings alone.

　3. The five year survival rates of groups 1) and 2) were as high as that of early gastric cancer, while that of group 4) was low (Fig. 1).

　4. Since it seems that there is an overlap between the category of type 5 and the classification of advanced cancer, it is necessary to separate them clearly.

　5. It is urgently needed to establish a new expression which mentions concisely on both gross findings and growth patterns of the cancer, taking into consideration the Borrmann's classification again.