健診を指向した胃癌の早期診断―集団医学の立場から

Early Diagnosis of Gastric Cancer Paying Special Attention to Routine Physical Check-up

　健診という言葉の意味が，外見病気でないものに対し，健康か否かを判断することであれば，それには次の2，3の検査方式が包含されるであろう．すなわち，胃疾患などで主に行われている集団検診，“人間ドック”と称されている短期入院総合精密検診，そして“外来ドック”とも呼ばれていて，個人の健康度精査を目的とし，通院の上で各種の検査を受ける健康診断などがある．いずれも慢性の疾患，成人病などの早期発見，早期診断を意図しているもので，前者は集団としての観察と方法を用いる集団医学であり，一臓器を中心に検査の行われることが多い．後二者は，個体の観察を行って身体全部あるいは一部の健康度の評価を行う臨床医学で，多臓器で多目的の検査を行うことが多く，その方法論は，前者に比べて明らかに異質のものであろう．このようなことから，三者を胃疾患・胃癌という疾病に限ってみても，同一レベルでの早期発見，早期診断を論ずることは困難が伴う．そこで小文は，現在筆者らの行っている胃集検，すなわち集団医学の立場をとり，得られた知見を胃癌の早期発見，早期診断という共通の目的から，広く“健診”にも指向しうるよう要点をしぼり，その考え方と実際について述べることとした．

　集団医学の立場から論ずる目的の1つは，申すまでもなく，現在のところ，胃癌の早期発見と早期診断は，胃集検によるのが最も効果的であるとされているからである．「早期発見に対する胃集検の効果」の章で後述するように，多くの点で評価されている．

　Now there is no doubt that gastric mass screening is the best way to detect early cancer in a high rate. However, for yet better results a more systematic and effective method is necessary. It is also desirable that such a method can be applied to screening of gastric cancer for individuals who visit the hospital in the form of physical check-up. In this paper are described chiefly the results of gastric mass screening at the Center for Adult Diseases. Osaka.

　Although the ratio of early gastric cancer to all cancer cases of the stomach is slightly elevated in the group who received mass screening before (noninitial screening), a higher rate of detection of early gastric cancer is observed in the group who underwent mass examination for the first time (initial screening). Furthermore, the number of examinees in the initial screening tends to decrease with the increase of those in the non-initial screening.

　Therefor, we believe we should attach importance to the group firstly examined concentrating on the age group 40～69, who have a high prevalence, especially on the community group. We also believe that the two to three years interval for each examination is most eflicient and effective when we take into account the changing rate of incidence of early gastric cancer in the group previously examined and our knowledge about the natural history of early gastric cancer.

　Physical laborers showed a high rate of detection in early gastric cancer compared with any other ones.

　Besides, after the mean 6.1 follow up years, the incidence of gastric cancer was two to three times higher in cases diagnosed as gastric ulcer than in those diagnosed as the other benign diseases at the initial examination.

　More than half of cancers belonged to early cancer. Gastric ulcer seems thus the most important subject to be encouraged in the detection of early cancer after the detailed examination.

　At present there is no other method than X-ray examination as a first step to early diagnosis of gastric cancer. Although it can remain simply as a method of screening the examinees from gastric cancer, proficiency with a certain fixed system of examination (exposure and interpretation of the films) makes it possible to diagnose cancer with less overlooking.

　In this respect is described a most standard way of indirect X-ray exposure and its propagation together with several points to be attended to in early detection and diagnosis of gastric cancer on the basis of mass screening. We deem it very important in excavated types of early cancer to look into the wall rigidity accompanied by en face findings and in protruded type to scrutinize filling defect accompanied with non-specific and indefinite findings. We have also referred to the fact that instead of the kinds of complaints hitherto considered important it would broaden the possibility of early detection to pay more attention to their nature such as gradual increase, continuity, complaints never experienced before and resistance against curative effect.