Peripheral progenitor cells (PBPC) in supportive care after high-dose chemotherapy in breast cancer.

Hemopoietic growth factors (HGF) and leukapheresed peripheral progenitor cells (PBPC) are increasingly used for supportive care in high-dose chemotherapy (HDC) of solid tumors. Presently, therapeutic protocols with cyclic HDC plus PBPC support are successfuly used in breast cancer patients. Administration of PBPC significantly influences hemopoietic recovery in terms of shortening the pancytopenia period which reduces the risk of dangerous complications, especially the risk of infection. As a certain controversy exists about efficacy of this therapy, large randomized studies are conducted to find more accurate conclusions. In 1998 National Cancer Institute (NCI) gave top priority to four randomized studies of HDC with PBPC support. In recent years, rising yields of PBPC are obtained. The use of new combinations and dosages of hemopoietic growth factors leads to a significant increase of progenitor cells circulating in peripheral blood. Effective mobilization regimens combinations of chemotherapy and cytokines - enable to increase the numbers of circulating progenitors as much as 100-fold. Another aspect, how to minimize the risks is to reduce the transplant volume and so reduce the amount of cryoprotective agent DMSO (dimethyl sulfoxide) and hemolysed erythrocytes. This led to the idea to use only whole blood enriched for PBPC. At present it has been used also in our patients. The results show that enriched whole blood can be used as sufficient substitution for support in intensive cyclic chemotherapy in breast cancer patients.