PERIPHERAL-BLOOD MONONUCLEAR-CELLS ARE A RELIABLE INTERNAL STANDARD FOR THE FLOW CYTOMETRIC DNA ANALYSIS OF FROZEN MALIGNANT BREAST BIOPSIES

DNA ploidy and S-phase estimations are widely used as prognostic indic ators in treatment decisions for breast cancer patients. For accurate calculation of the DNA index there is a need to identify the G(0)G(1) diploid peak position. This study tested the reliability of peripheral blood mononuclear cells (PBMCs) as a diploid internal standard in the flow cytometric DNA analysis of 60 frozen malignant breast tumors. Fo r each tumor, PBMCs were added to a duplicate sample prior to staining . There were 55 tumors with interpretable histograms; 18 were DNA dipl oid, 37 were DNA aneuploid, and all tumors had coefficients of variati on < 5.0%, For each of the 55 tumors, whether diploid or aneuploid, th e addition of PBMCs gave a unimodal peak at the diploid peak position, The results show that PBMCs are a reliable standard to identify the G (0)G(1) diploid peak position, (C) 1996 Wiley-Liss, Inc.