Use of granulocyte colony-stimulating factor (G-CSF) for mobilizing peripheral blood stem cells: risk of mobilizing clonal myeloma cells in patients with bone marrow infiltration.

Peripheral blood stem cells have been used for autologous reconstitution of haemopoiesis after high dose cytotoxic therapy and produce similar disease response rates as autologous bone marrow transplants. Peripheral blood stem cell transplants are an especially attractive option for patients in whom marrow harvest is not feasible due to bone marrow damage or infiltration. Recombinant growth factors mobilize adequate numbers of stem cells from the marrow but their effect on tumour cell circulation kinetics is not known. We report a patient with multiple myeloma and bone marrow infiltration in whom the use of G-CSF for stem cell mobilization led to release of plasma cells into the peripheral circulation and contamination of the stem cell harvest.