早期胃癌の変貌―X線診断の立場から

Transfiguration of Early Gastric Cancer, with Special Reference to the Radiologic: Examination and Diagnosis

　1980年1月，本誌に胃病変の時代的変貌が特集された．その誌上で，高木ら^1）は，早期胃癌の時代的変貌を次のようにまとめている．（1）早期胃癌の症例数の増加（手術例の28.1％）が最も大きな変貌である．（2）ⅠおよびⅡaは，数のうえでは増加しているが，早期胃癌全体の中では比率は減少している．（3）Ⅱc＋Ⅲ，特にⅢが減少しているのに反して，Ⅱcが増加し，48％と半数近くを占める．（4）Ⅱbの増加（4％となる）．（5）5mm以下の微小癌の発見数の増加（11例）．（6）早期胃癌の占居部位をみると，Mの癌の頻度がAの癌よりも多くなり，逆転しているのが特徴である．しかし，Cの癌の増加傾向は少なかった（進行癌ではCの癌の増加傾向がみられた）．（7）多発癌の増加（3.1％→6.3％→11.4％）．

　また，加藤ら²⁾は病理組織学的立場から，切除された全胃癌（進行癌ならびに早期癌）では，分化型癌と未分化型癌の比（DUR）が男女ともに低下傾向がみられ，分化型癌の相対的減少があることが示唆されたと報告している．そして，胃癌の占居部位については，DURは，元来胃幽門腺領域である部位では著変なかったが，元来胃底腺領域である部位では著しく低下した（推計学的に有意）．特に，萎縮や腸上皮化生の起こりやすい部位の低下は顕著であったと述べている．

　Transfiguration of operated early gastric cancer was studied from the standpoint of radiologic examination and diagnosis of the stomach. It was revealed that total number of operated early gastric cancer has markedly increased. Especially, the number of depressed early gastric cancer obviously increased in contrast to decrease in the number of polypoid early cancer operated. Depressed early cancer on the anterior wall, upper portion and greater curvature also increased in number. The number of minute cancer and cancer in the fundic gland mucosa also has increased in the recent years. It is considered that such an increasing tendency in the operated number of early gastric cancer has been brought about by the progress of the radiologic examination.

　On the contrary, the operated number of Type Ⅱb lesion has still remained unchanged, probably due to the fact that it is not visualized under fluoroscopy even with image intensifier of high resolution quality. In addition, a definite line should be drawn as to the equivocal definition of Ⅱb-like or Ⅱb-simulating lesion.

　It deserves mentioning that difference in the macroscopic and radiologic characteristics between differentiated and undifferentiated type of gastric carcinoma has been clarified, based on intensive comparative studies on radiologic and pathologic findings. According to Nakamura, early diagnosis of linitis plastica type carcinoma can be made by discovering a Ⅱc lesion in the fundic gland area, without converging folds and measuring less than 2 cm in diameter. Theoretically, a Ⅱc lesion like this may easily be diagnosed in the radiologic examination because its depression is rather deep with sharply defined limits.

　In Japan, from now on, the number of cases of undifferentiated type of carcinoma is anticipated to increase compared to that of differentiated type of carcinoma. This tendency, however, is not shown yet in the figure drawn out from our data.

　Incidence and reported cases of narrowing of the pyloric lumen due to depressed early cancer are very few, and scarcely discussed in the literature.

　In these recent years we have been putting our greatest efforts on improving radiologic equipments. Acutually the improved radiologic equipments have drastically raised the number of detected cases of early gastric cancer. What in urgent need are to improve radiologic equipments based on rational radiologic examination theory and to develop human resources.