RELEASE OF PERIPHERAL-BLOOD PROGENITOR CELLS DURING STANDARD-DOSE CYCLOPHOSPHAMIDE, EPIDOXORUBICIN, 5-FLUOROURACIL REGIMEN PLUS GRANULOCYTE-COLONY-STIMULATING FACTOR FOR BREAST-CANCER THERAPY

Background. High dose chemotherapy with the support of peripheral bloo d progenitor cells (PBPC) is increasingly used in the treatment of sol id tumors. Although the best method of PBPC mobilization is still unde r investigation, it should be optimized for different tumor types to o btain antitumor effect and mobilizing activity. The authors report the se results in terms of the number of PBPC released and the time of max imum mobilization induced by standard dose cyclophosphamide, epidoxoru bicin, 5-fluorouracil (CEF) (cyclophosphamide 600 mg/m(2), epidoxorubi cin 60 mg/m(2), 5-fluorouracil 600 mg/m(2)) plus granulocyte colony st imulating factor (G-CSF) in patients with breast cancer. Methods. Peri pheral blood progenitor cells were studied by clonogenic assay of gran ulocyte macrophage colony-forming units (CFU-GM), megakaryocyte colony -forming unit (CFU-Meg) and erythrocyte burst-forming unit (BFU-E) and by flow cytometric analysis of CD34+ cells in 12 patients with early breast cancer throughout three cycles of CEF chemotherapy plus G-CSF. Results. Colony assays and CD34+ cell determination were performed on 111 and 151 blood samples, respectively. The peak of CFU-GM and CD34cells occurred consistently at day 11 throughout all three cycles. At day 11. of the first cycle, the median peak values were 2223 CFU-GM/mL and 256 CD34+ cells/mu L. A progressive decrease in peak value from t he first to the third cycle was observed. Conclusions. Standard dose C EF chemotherapy plus G-CSF is a disease specific regimen allowing PBPC mobilization without any relevant toxicity. Maximum mobilization was recorded at day 11 of the first cycle.