FLOW CYTOMETRIC DNA ANALYSIS AND BREAST-CARCINOMA PROGNOSIS

Flow cytometric DNA analysis (FCM) simultaneously provides two parameters which characterize a breast tumor: 1) a DNA index, which is a real marker of a tumor stem line, leads to a classification based on DNA-ploidy; 2) the percentage of cells in DNA synthesis phase (S%), which is linked to tumor proliferation. At the time of diagnosis, it is possible with FCM to routinely measure these parameters which are appraisable on cytopunctures. The prognostic value of FCM in breast carcinomas became clear at the end of the eighties, when retrospective studies on paraffin-embedded material showed that S% was an independent prognostic factor, compared to classical parameters. Since 1981, we have performed FCM analysis on fresh tumors. We have studied 685 patients who were first operated on and defined three groups based on S% values for DNA-diploid (D) and DNA-aneuploid (A) tumors: group 1 (low S% for D and A), group 2 (high S% for D and intermediate S% for A), group 3 (high S% for A). Five year overall survival percentages are respectively 90%, 69% and 41%, which is significantly different (P < 0.0001). The same is also the case for disease-free survival (P < 0.0001). In a Cox multivariate analysis, this FCM classification was an independent and powerful prognostic indicator for overall survival and for disease-free survival. Due to the characteristics of breast cancers diagnosed in screening programs, traditional prognostic factors may lose their predictive value. These results show that DNA flow cytometry should be included in prognostic studies for these patients.