陥凹型早期胃癌の深達度診断―部位によるX線診断の問題点

Problems Associated with Radiographic Diagnosis of Depth Invasion According to Gastiric Cancer Sites

要旨　X線による陥凹型胃癌の深達度診断の現状を分析し，その問題点と対策について，部位別，粘膜領域別に検討した．深達度診断の的中率はm癌では63.2％，sm癌では49.2％，早期癌類似進行癌では79.9％であった．m癌では前壁の病変，胃底腺粘膜領域の病変，未分化型癌，Ulを合併した病変は陥凹の境界が鮮明で，陥凹底の凹凸が著明なものが多く，ひだの先端の変化も著明なため，sm癌または進行癌と誤診される傾向がみられた．sm癌では噴門部と幽門部は解剖学的，X線学的に特殊な部位であり，従来の診断法が当てはめにくいため，的中率は特に悪く，前者では組織所見よりも浅く，後者では深く読み過ぎる傾向がみられた．しかし，sm癌全体についてみると，進行癌と診断された例は少なく，sm癌の約半数はm癌と誤診されていた．このことは，従来の診断法には，m癌とsm癌の鑑別に問題が残されていることを物語るものであり，今後，sm浸潤に対する，より精度の高い指標の開発と同時に，従来の診断指標をより有効に活用するための対策の検討が必要である．

　The state of the art of radiographically diagnosing depth invasion in depressed type gastric cancer were described to elucidate problems and strategies against them with respect to the cancer sites and mucosal regions. Accuracies of radiographic diagnosis were 63.2%, 49.2%, and 79.9%, from m, sm, and early cancer-mimicking advanced cancers, respectively.

　In m cancer, lesions involving anterior wall and gastric fundic glands, undifferentiated type and ones accompanying ulcer tended to have discrete border with marked unevenness in depressed area and distinct change in the tips of mucosal folds. Because of these characteristics m cancers were likely to be erroneously diagnosed as sm or advanced cancers.

　In sm cancer, the cardia and pylorus are distinguished from other areas in that traditional diagnostic principles are not applied because of anatomical and radiographic characteristics. Therefore, accuracies are extremely low in these areas, the cardia being underestimated and the pylorus being overestimated. However, there are few sm cases erroneously diagnosed as having m cancer.

　Thus, m and sm cancers are not easily differentiated. Therefore, it is mandatory that new diagnostic parameters with higher accuracy should be developed and that traditional diagnostic parameters should be further discussed to make problems explicit and to withdraw strategies against them.