Methodological aspects on cytochemical DNA assessment of adenocarcinoma of the endometrium by means of image and flow cytometry using conventionally formalin-fixed and paraffin-embedded specimens.

Sometimes widely diverging results have been reported as regards the nuclear DNA ploidy pattern of adenocarcinomas of the endometrium. Since such discrepancies might be due to differences in the techniques applied, it seemed worthwhile to investigate this possibility in conventional uterine curetted specimens. In order to obtain a high incidence of tumours with cancer cell nuclei showing "aneuploid" DNA distribution pattern, a selection was made, so that only those adenocarcinomas that had led to a fetal outcome of the neoplastic disease were examined. The results of two image cytometric (ICM) techniques for cytochemical nuclear DNA assessments were compared. One was direct photographic cytometric measurements on Feulgen-stained sections; the other was densitometric assessments on isolated tumour cell nuclei of deparaffinised and disintegrated specimens. In 39 cases out of 43 the DNA ploidy pattern was the same by means of the two techniques. However, about half the numbers of the specimens (40 out of 83) were lost during the deparaffinisation and disintegration procedure. As far as could be found from a limited study on 20 (out of the 43) selected cases, these losses of specimens became even greater when the flow-cytometric (FCM) technique was applied on the deparaffinised specimens; about one third of these specimens were not possible to evaluate. In addition, in those where assessments by means of FCM could be made, the DNA ploidy pattern obtained differed from that of the two ICM techniques in not less than 80% of the cases. Broad peaks and high amounts of counts in the background in the DNA histograms indicated that most of the DNA assessments made by means of FCM on archival material of the present kind of curetted specimens of endometrial adenocarcinomas gave no reliable results. Consequently, differences in the techniques applied in cytochemical assessments of the nuclear DNA distribution pattern in endometrial carcinomas can explain the more or less controversial results reported from different laboratories.