Cytometry of breast carcinoma: Significance of ploïdy balance and proliferation index

Image cytometry of DNA distribution in fine needle biopsies of breast carcinomas at first diagnosis was performed to see if there were significant differences in DNA histograms between patients having very different outcome but same tumor histological typing and similar therapy. Two groups of patients were considered retrospectively: the first (20 patients) with survival time shorter than 5 years and the second (20 patients) with survival time longer than 10 years. Seven benign tumors were used as controls. Ten ploïdy classes were defined. The frequencies of cells in those classes were used as independent features in a supervised multivariate analysis. The advantages of this approach was pointed out with respect to the four-type classification of Auer. The scattering of DNA histograms within the feature space showed that a subgroup of patients with poor prognosis was clearly separated from a subgroup of patients with good prognosis but both long survival patients and short survival patients were scattered in between. In order to replace the multivariate classification of histograms by a simpler approach, two parameters were computed which explained most of the scattering in the feature space: the ploïdy balance (difference between the percentages of euploid and aneuploïd cells) and the proliferation index (percentage of cells between peaks). The scattergram of patients according to these parameters showed again that some DNA distributions were specific for either good or bad prognosis. But the separation was uncertain for seven short-survival patients and six long-survival patients. For six patients, the DNA distributions were very similar between long and short survival times. Those patients thus could not be separated even by means of discriminant analysis. The main conclusion of this study was that, for a significant number of patients, the objective multivariate classification of tumors DNA profiles is of little assistance to the pathologist who has to give a prognosis for the one patient under consideration.