PROGNOSTIC VALUE OF DNA-PLOIDY USING FLOW-CYTOMETRY IN 1301 BREAST-CANCER PATIENTS - RESULTS OF THE PROSPECTIVE MULTICENTER MORPHOMETRIC MAMMARY-CARCINOMA PROJECT

The literature on breast cancer reports conflicting prognostic results with respect to DNA ploidy of now cytometric DNA histograms. This mig ht result from different DNA ploidy classification methods. Our study evaluated the prognostic power of DNA ploidy, using different classifi cation methods, in a large prospective group (n = 1301) of breast canc er patients. Flow cytometric DNA histograms obtained from fresh frozen material were interpreted with use of a commercially available comput er program. On the basis of the number of stemlines and the DNA index, we classified the DNA ploidy by different methods. In all of the case s, the classification method ''DNA diploid versus DNA nondiploid'' pro vided the best prognostic significance for overall survival (OS) (Mant el-Cox (MC) = 5.4, P = .02; relative risk (RR) = 1.3, P = .05) and for disease-free survival (DFS) (MC = 11.8, P = .0006; RR = 1.3, P < .05) . This was also true for the OS of the lymph node-positive (but not th e lymph node-negative) subgroup (MC = 4.1, P = .04; RR = 1.3, P = .05) . In subgroups classified on the basis of tumor size, DNA ploidy showe d prognostic significance for DFS only in the subgroup of tumors small er than 2 cm and larger than 5 cm. In multivariate analysis, DNA ploid y showed no additional prognostic power to lymph node status and tumor size. The classification ''DNA diploid versus DNA nondiploid'' was mo stly consistent with respect to prognostic power for OS and DFS, espec ially in small or lymph node-positive tumors. The RR of DNA nondiploid patients was only marginally higher, however, so large study groups a re required to reach statistical significance. This could partly expla in the disagreements in the literature. Therefore, DNA ploidy seems to be of little clinical importance in breast cancer patients, compared with other prognostic parameters.