HEMATOPOIETIC PROGENITOR-CELL COLLECTION AND NEOPLASTIC CELL CONTAMINATION IN BREAST-CANCER PATIENTS RECEIVING CHEMOTHERAPY PLUS GRANULOCYTE-COLONY-STIMULATING FACTOR (G-CSF) OR G-CSF ALONE FOR MOBILIZATION

Background: We compared hematopoietic progenitor cell (HPC) collection and neoplastic cell contamination in breast cancer patients given cyc lophosphamide (CTX) plus granulocyte-colony stimulating factor (G-CSF) or G-CSF alone for mobilization. Patients and methods: In 57 stage II -III breast cancer patients, CD34+ cells, colony-forming units-granulo cyte macrophage (CFU-GM), early HPC and breast cancer cells were count ed in HPC collections obtained after CTX plus G-CSF (n = 27) or G-CSF- alone mobilization (n = 30). Results. The CD34+ cell collection was ab out two-fold greater after CTX plus G-CSF mobilization (11.0 +/- 7.9 v s. 5.8 +/- 3.5 x 10(6)/kg, P < 0.001). Similarly, the total number of CFU-GM, CD34+CD38- cells and of week-5 cobblestone area forming cells (CAFC) collected was significantly higher in patients mobilized with C TX plus G-CSF. Breast cancer cells were found in the apheresis product s of 22% of patients mobilized with CTX plus G-CSF and in 10% of patie nts mobilized with G-CSF alone (P = 0.36). Of seven patients who faile d G-CSF-alone mobilization and eventually underwent chemotherapy plus G-CSF mobilization, none had cytokeratin-positive cells after G-CSF mo bilization, whereas four out of seven had cytokeratin-positive cells a fter chemotherapy plus G-CSF (P = 0.07 by chi(2) test). Conclusion: Th e CTX plus G-CSF mobilization protocol was associated with a significa ntly higher HPC collection. However, this benefit was not accompanied by a reduction in the incidence of tumor-contaminated HPC graft.