The risk of tumor cell contamination in peripheral blood stem cell collections

Peripheral blood stem cell (PBSC) reinfusions are being used with increasing frequency in lieu of, or in addition to, autologous bone marrow transplantation (ABMT) to rescue cancer patients from the myeloablative effects of high-dose chemotherapy. However, the incidence and quantity of tumor cell contamination in PBSC collections has not been widely investigated. This paper reviews the existing data and presents new information to demonstrate that tumor cells are detectable in PBSC harvests from patients with a variety of malignancies. Furthermore, their presence in peripheral blood may have prognostic and clinical significance. Areas of future research and applications for PBSC technologies are also discussed.