Application of peripheral blood progenitors to dose-intensive therapy of breast cancer

Dose-intensive therapy has been used with increasing frequency in the treatment of women with breast carcinoma. This therapy requires chemotherapeutic agents that exhibit a steep dose-response curve and that have myelosuppression as their primary dose-limiting toxicity. To hasten or to rescue hematologic function after dose-intensive therapy, a hematopoietic rescue is used. The source of this rescue has traditionally been autologous bone marrow cells. However, circulating peripheral blood progenitor cells can also reconstitute hematopoiesis after dose-intensive therapy. The only prerequisites are that hematologic recovery is at least comparable and that survival is not adversely affected by the source of the stem cell graft. Peripheral blood progenitors can be procured in sufficient numbers after priming or mobilization with chemotherapy and/or hematopoietic growth factors. Peripheral blood progenitors collected in this fashion have led to complete and sustained hematologic reconstitution in women with metastatic breast cancer involving the marrow. In addition, peripheral blood progenitors can be used to augment autologous bone marrow grafts, further hastening hematologic recovery after dose-intensive therapy. Future studies will examine the role of peripheral blood progenitor support of multiple doseintensive cycles in women with breast cancer.