DETECTION OF TUMOR-CELLS IN THE BONE-MARROW, PERIPHERAL-BLOOD, AND APHERESIS PRODUCTS OF BREAST-CANCER PATIENTS USING FLOW-CYTOMETRY

One of the possible drawbacks to autologous bone marrow (BM) and perip heral blood progenitor cell (PBPC) transplantation in breast cancer pa tients is the potential for tumor cell contamination in the transplant ed product. To assess the presence of breast cancer cells, we have dev eloped a flow: cytometric method using cytokeratin-FITC and CD45-phyco erythrin (PE) to detect very low levels of cytokeratin-positive (CK+) tumor cells in mononuclear cell (MNC) preparations. In a model system using PBMNC and the breast cancer cell line CAMA, the sensitivity of d etection of this flow-cytometric method was one tumor cell in 200,000 MNC. This method was used to evaluate BM, PB, and apheresis products ( AP) from 44 patients with metastatic breast cancer. When possible, sta ined cytologic examination was performed on smears of the unprocessed specimens and on flow cytometry-sorted cells. Results indicated that C K+ tumor cells could be detected by flow cytometry in all three specim en types. When present, however, the tumor content (per MNC) tended to be higher in BM than in PB or AP. Samples from a given patient taken serially over the course of chemotherapy revealed variable results, su ggesting that the presence of tumor contamination may be sporadic and requires evaluation of each stem cell product. Of 75 samples tested wi th both now cytometry and cytology, the results were concordant in 54 cases (72%). In the remaining samples, flow cytometry only was positiv e in 15 cases (20%), and cytology only was positive in six cases (8%). This flow-cytometric technique is useful in the evaluation of transpl ant products for CK+ tumor cell contamination.