日本の早期食道癌の定義，病理，実状，予後について

Early Esophageal Cancer: Definition, Pathology, Present Status and Prognosis

　日本における早期食道癌の報告は，1966年東北大山形ら¹⁾，東京女子医大中山ら²⁾の発表以来，しだいにその数もふえつつあるが^3)～5)，年間に取扱う食道癌の数よりみれば極めて微々たるものである．このことは，近年食道の各種検査法が発達したにもかかわらず，一つには食道の検査の機会が少ないためと考えられる．

　一方，かかる早期食道癌の定義をめぐって種々の論義^6)～9)がくり返され，食道癌取扱い規約¹⁰⁾では「癌浸潤が粘膜下層までにとどまり，転移のないもの」すなわちstage 0癌と定義されている．

　Early carcinoma of the esophagus is now defined as cancer whose depth of invasion is at most confined to the submucosal layer with no metastasis, or, in short, stage-0 carcinoma. Based on this definition, we have collected early carcinama of the esophagus reported in Japan, which amounted to 58 cases up to Nov. 1975.

　Symptoms were mostly slight such as sense of stenosis or chest pain at swallowing. Duration of sypmtoms was also short, mostly less than 2 months. Accurate diagnosis was most effectively obtained by the combined use of x-ray, endoscopy, biopsy and cytologic study. Elevated type of cancer was easy to diagnose, while superficial type with spreading tendency was liable to error in diagnosis.

　Macroscopically most of early esophageal cancer belonged to protruded type with well-defined margins. A few cases were of flat type with ill-defined borders. Small cancers less than 30 mm in diameter, including 6 microcarcinomas under 10 mm in diameter, were seen in 55 per cent.

　Histologically squamous cell carcinoma accounted for 90 per cent. Moderately differentiated carcinoma was most often seen, followed by well differentiated one. Exceptional types included 2 cases of adenocarcinoma, 2 of adenocarcinoma and 3 of carcinosarcoma. Depth of invasion was intraepithelial in 16 per cent, to muscularis mucosae in 5 per cent and to the submucosa in 79 per cent. A series of superficial carcinoma with lymph node metastasis we have additionally collected in comparison showed in all cases invation to the submucosa.

　One of us, Nabeya, has assumed that type of growth of early esophageal cancer be divided into 3 stages; initial minute type (micro-type), intracavity extending type and intramurally spreading type, and that protecting mechanism of organism be responsible for their res-pective development.

　Treatment and prognosis of early esophageal cancer are becoming better, but we are still confronted with a great problem how to detect cancer in early stage.