Heterogeneity of DNA ploidy in patients with undifferentiated carcinomas of the stomach.

DNA ploidy was determined by cytophotometric DNA analysis in 20 patients with undifferentiated carcinomas of the stomach with serosal invasion. Measurements of DNA content were performed in 100 cells each in intramucosal, submucosal, muscular, and subserosal parts of a tumor. According to dispersion on the DNA histogram, DNA ploidy patterns were divided into low and high ploidy groups. Fourteen tumors (70%) showed the same ploidy in every layer (homogeneous DNA ploidy), 13 (65%) were low ploidy and, 1 (5%) was high ploidy. Heterogeneity of DNA ploidy was observed in the remaining six tumors (30%), which showed low ploidy in the mucosa, but high ploidy was observed in one or two deeper layers. In the six with heterogeneous DNA ploidy, there was more frequent metastasis to the lymph nodes (100%) and to the peritoneum (67%) than those with homogeneous DNA ploidy (50% and 21%, respectively). Cytophotometric DNA analysis of cells of undifferentiated gastric tumors suggested that there may be behavioral changes, depending on the degree of penetration into the gastric wall.