[Studies on DNA content in ploidy patterns of esophageal cancer]

The present study was undertaken to evaluate the nuclear DNA content of esophageal cancer cells consequent on the process of growth and progression of the cancer. In experimental animal studies, 47 esophageal cancers were induced in male Wistar rats by oral administration of N-amyl-N-methylnitrosamine (AMN) and were analysed in the study of ploidy patterns. The study was also carried out to determine the DNA content in the ploidy patterns in man. Primary tumors associated 421 metastatic lymph nodes in the 62 patients with thoracic esophageal cancer were subjected for the study of ploidy patterns. The nuclear DNA content was determined by means of flow cytometry. In the study of the experimentally-induced esophageal cancer in rats, aneuploidy was found in 18% at a depth of submucosa, 30% at proprial muscle, 59% at adventitia, and in 50% at a depth of neighboring structures, respectively. Clinically in man, the incidence of DNA diploidy and aneuploidy in the 62 primary cancers was 56% and 44%, respectively. In the 421 metastatic lymph nodes, diploid was found in 73% and aneuploid in 11%, while the combination of diploid and aneuploid was observed in 16%. Difference in the DNA index (DI) between the primary cancers and metastatic lymph nodes was found in 29 cases (46.8%), and the difference increased with progression of the cancer. Two hundred and ninety seven metastatic lymph nodes of 29 cases were subdivided into 4 groups based on the extent of the cancerous nests, and the DI value was found to be increased in proportion to the extension. With the results, the DI value of esophageal cancer appeared to be changed dependently by the variation of cell populations in the cancer or in the DNA content of the cancer cells.