Relevance and clinical implications of tumor cell mobilization in autologous transplantation of multiple myeloma and non-hodgkin's lymphoma

Autologous transplantation of peripheral blood (PB) hematopoietic stem cells is a widely used strategy for reconstitution of blood cells following high-dose chemotherapy for hematologic malignancies, such as multiple myeloma and non-Hodgkin's lymphoma. Stem cells for transplantation are usually obtained from PB after treatment with chemotherapy with or without cytokine [usually, granulocyte colony-stimulating factor (G-CSF)] or after treatment with cytokine alone (such as G-CSF). The use of autologous peripheral blood stem cells for transplantation is associated with the risk of contamination of the graft with tumor cells and whether this impacts response rates, progression-free survival, and overall survival is still debatable. This review summarizes the controversy around tumor cell mobilization (TCM), complexity of detection of minimal residual diseases, available diagnostic tools, differences in TCM with available mobilization regimens, and the potential effect of TCM on clinical outcome.