Flow-cytometric analysis of DNA content in postmortem tissue

In order to determine the heterogeneity of ploidy in disseminated cancer, we assessed the suitability of postmortem tissue for flow-cytometric analysis of cellular DNA content. Forty tissue samples from various tumor-bearing sites in 12 patients with widely metastatic cancer were analyzed. In eight cases studied there was a single unimodal ploidy level in all disease sites studied. The remaining four cases revealed bimodal tumor populations present in different proportions in the various sites studied. No difference in ploidy could be detected between irradiated and nonirradiated sites in patients who had received radiation therapy. Samples taken from normal tissues all revealed diploid DNA content, suggesting that DNA fluorescence is not altered in the immediate postmortem period. Systematic analysis of cellular DNA content in autopsy material is feasible and may contribute to our understanding of patterns of metastatic spread in patients with cancer.