Natural history of gastric carcinoma with special reference to the "early cancer" stage: a mitotic index study on original and recurrent carcinomas.

The natural history of gastric carcinoma, especially during the "early cancer" stage, was investigated in terms of chronological changes in the mitotic indices of the carcinoma. Nine cases of gastric carcinoma which recurred after long periods of time were analyzed. In seven cases in which a second operation was performed after 2 approximately 14 years, the mitotic indices of the recurrent carcinomas were about the same as or slightly higher than those of the original ones. On the other hand, in 3 cases in which second operations were done within 2 years, the mitotic indices were lower in the recurrent carcinomas. No general trend toward a change in mitotic indices, relative to either the surface topography or the depth of the stomach wall at the site of the carcinoma, was observed, although there was one exceptional case in which a distinctly elevated mitotic index was obtained at the site of the nodular down-growth of the carcinoma associated with apparent morphological features of progression. In 5 out of 7 cases with lymph node metastasis, the mitotic indices in the metastatic site were slightly higher than in the original carcinoma. The overall impression gained from the present study was of the unchangeability of the cell kinetics of gastric carcinomas during the long early cancer stage, although the results also indicate the gradual or abrupt progression of carcinomas during their natural history. The mechanisms which produced reduction in the growth rates of carcinomas within 2 years after operations are discussed.