ABSENCE OF BREAST-CANCER CELLS IN A SINGLE-DAY PERIPHERAL-BLOOD PROGENITOR-CELL COLLECTION AFTER PRIMING WITH CYCLOPHOSPHAMIDE AND GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR

The effect of priming on occult tumor cell involvement of peripheral b lood (PB) and PB progenitor cell (PBPC) collections is poorly characte rized. Using sensitive immunocytochemistry (ICC) and tumor clonogenic assays (TCA) specific for epithelial-derived tumor cells, hematopoieti c specimens were analyzed for PBPC and occult tumor cell involvement i n 28 patients with chemotherapy-sensitive stage IIIB or IV breast canc er. Before PBPC priming, tumor was detected by ICC in PB of 1 of 23 (4 %) patients and in bone marrow (BM) harvests of 4 of 27 (15%) patients . Fifteen days after cyclo-phosphamide and granulocyte-macrophage colo ny-stimulating factor (GM-CSF) priming, 2 of 28 (7%) patients had ICC- positive PBPC collections. The median amplification of CD34(+) PBPC du ring this time was over 19-fold (range, < 1 to 199), One patient had p retreatment tumor involvement of both PB and BM. One patient grew tumo r colonies in TCA; the PB and BM were ICC- and TCA-positive, but the P BPC collection was ICC-positive but TCA-negative, After cytoreduction with conventional-dose chemotherapy, patients with advanced breast can cer and histologically negative BM biopsy specimens have rare tumor ce ll involvement of PB and BM. Despite effective PBPC priming with cyclo phosphamide and GM-CSF, clonogenic breast cancer cells were not found in the PBPC collection performed on day 15. (C) 1995 by The American S ociety of Hematology.