Efficacy of combined image and flow cytometric DNA assessments in human breast cancer: a methodological study based on a routine histopathological material of 2024 excised tumour specimens.

In 2024 excised specimens of malignant tumours of the female mammary gland. the nuclear DNA distribution pattern of the neoplastic cells was assessed by means of two procedures. One was image cytometry (ICM); here, all the 2024 samples were assessed. The other was flow cytometry (FCM) where 1336 specimens were analysed. In 829 of the 2024 tumour nodules the results of ICM and FCM could be compared. The efficacy of both techniques alone was about 80%; that of the combination was about 60%. In the ICM procedure the main reason for the reduction of samples was the failure to obtain representative specimens. The losses in the FCM method were due to poor quality of the histograms (too much background noise and too broad coefficients of variation). In addition, in as much as one third of all the cases, no specimens were set aside for FCM assessments. In 16% of the samples, where the results of the ICM assessment could be compared with those of the FCM analyses, completely diverging DNA ploidy patterns were obtained. The discrepancy was caused by differences in the interpretation of the histograms. In addition, the calculations of so-called S-phase fractions from the diploid FCM histograms was found to be associated with methodological errors, further contributing to differences in the DNA assessments by means of ICM and FCM. Nevertheless, it was advantageous to use combined ICM and FCM assessments, particularly in the interpretation of DNA histograms of uncommon types.