This prospective study quantifies the response of hemoglobin and other blood factors to Epoetin alpha (EPO) administration in the course of pre-operative chemotherapy in breast cancer. Blood count time series were analyzed in 38 primary breast cancer patients with/without EPO during the course of pre-operative chemotherapy with epirubicin and paclitaxel. EPO injections improved blood counts in 'anemic' patients (< or =12.0 g/dl) receiving chemotherapy, but had little effect when administered to patients with higher hemoglobin concentrations. On the average, without chemotherapy, hemoglobin concentrations drifted toward about 11.1 g/dl without EPO but could be maintained at near 12.0 g/dl with EPO. In conclusion, there is potential for improved anemia management using EPO during pre-operative chemotherapy, which not only benefits quality of life but could also influence long-term survival in breast cancer through improved tumor oxygenation.