DNA content of diffusely infiltrative carcinomas in the stomach.

DNA content of diffusely infiltrative carcinomas of 15 Japanese patients, ranging in age from 38 to 65 years, was determined by cytofluorometry, using paraffin sections which were available for histological examination. Sections were stained with 0.0025% propidium iodide. By measuring the fluorescence intensity of at least 50 mitotic cells, ploidy patterns of the cancers were determined, whereas a control of the diploid DNA content was set by measuring the fluorescence intensity of mitotic cells in the non-cancerous gastric mucosa; only metaphase nuclei in the sections were considered to have a whole amount of nuclear DNA in the cytofluorometric measurement. In the present study, it was found that most of the diffusely infiltrative carcinomas consisted of a heteroploid cell line. Their stem DNA contents ranged between 2.8C and 4.8C (2C corresponds to a diploid amount of nuclear DNA). Of 15 cancers, four comprised a mosaic cancer of two different heteroploid cell lines. We encountered only one carcinoma containing a diploid cell line. However, this cancer also contained a heteroploid cell line. Six cancers contained a polyploid cell population, the DNA content of which was double of the stem DNA content. In most cases, the cancer cells distributed in the mucosal layer were also heteroploid, thereby suggesting a heteroploid origin of the diffusely infiltrative carcinomas.