A comparison of static cytofluorometry and flow cytometry for the estimation of ploidy and DNA replication in human breast cancer.

332 primary invasive breast carcinomas were analysed by static cytofluorometry and flow cytometry. The ploidy distributions were similar, and 54% of the tumors were judged DNA aneuploid by both methods. The coefficient of variation of the G0-G1 peaks ranged from 2.0 to 8% with both techniques, but the mean was somewhat lower with flow cytometry--4.1%, compared to 4.9% for the static measurements. The proportion of S-phase cells was possible to estimate from 80% of the flow histograms and 70% of the static histograms. S-phase was not estimated from the static histograms if less than 150 tumor cells were measured. With 160 tumors S-phase was measured by both methods. The range was 0 to 27% with the static measurements and 0.7 to 25% with flow cytometry. Corresponding mean values were 7.6% and 8.2%, which are similar to thymidine labeling index results with breast cancers reported in some studies. A close correlation was obtained (r = 0.927) comparing S-phase fractions estimated from aneuploid tumors with flow cytometry and static cytofluorometry if more than 200 cells were measured with the latter. The proportion of S-phase cells was significantly lower for the diploid tumors. We conclude that both techniques can be useful for the estimation of DNA ploidy and replication in human breast cancer.