A COMPARISON OF CYTOGENETIC STUDIES AND FLOW-CYTOMETRY IN BREAST CARCINOMAS

In this study, we compared genetic instability in 70 breast carcinomas analyzed by two different methods, cytogenetics and flow cytometry. T his comparison showed that each method has its strengths and weaknesse s. Flow cytometry detected aneuploidy in 60% of cases, but missed most of the cytogenetically near-diploid clones and clones with simple chr omosomal changes. Cytogenetics revealed chromosomal abnormalities in 5 0% of the samples. Simple chromosomal changes and multiploidy were rea dily detected by this method, but some of the clones with a high DNA i ndex: by flow cytometry were missed. The two methods gave correspondin g results in the majority of cases (54%). In 17 cases, both methods de tected matching abnormal clones (r = 0.93) but the DNA index was highe r than predicted by the chromosome numbers. Most of the discrepancies might be explained by tumor heterogeneity and insufficient numbers of cells available for cytogenetic analyses. In seven cases, single-cell abnormalities were found that corresponded to a pow cytometry peak. Mu lticlonality was present in 25% of aneuploid tumors. No association wa s found between metaphases in cytogenetic preparations and increased S -phase fraction of the tumors, but aneuploid tumors had a significantl y higher proliferation rate. Pooling data from both methods demonstrat ed that the majority of our samples were aneuploid (74%). (C) 1997 Wil ey-Liss, Inc.