DNA cytometry of primary breast cancer. Comparison of microspectrophotometry and flow cytometry, and different preparation methods for flow cytometric measurements.

In 18 biopsy specimens from human breast carcinoma a comparison was made between DNA measurements obtained by microspectrophotometry (MSP) of Feulgen-stained nuclei in imprints and flow cytometry (FCM) of nuclei stained with ethidium bromide. For each specimen FCM was performed both with ethanol-fixed cells and unfixed cells. In addition, single cell suspensions were made from other 11 fresh mammary cancer biopsies. Parts of these suspensions were analysed both by MSP (Feulgen-stained smears) and FCM (ethanol-fixed, mitramycin-stained cells). The MSP histograms show selected tumour cells and tumour-like cells. This explains the higher proportion of cells with DNA content above the 2 c level. A good agreement was found between the results obtained by MSP and FCM with regard to the ploidy of the DNA stemline(s). FCM of fixed cells (multiple-step procedure) yielded a slightly lower proportion of diploid cells than FCM of the unfixed cells (one-step procedure), probably owing to loss of small cells during the different preparation steps. It is concluded that the results from DNA-histograms obtained from MSP and FCM can be compared as to DNA-stemline ploidy of the cell population but not as to the proportion of cells with non-diploid DNA-content.