The Incidence of Tumor Cell Contamination of Peripheral Blood Stem Cells: A Meta-Analysis to Evaluate the Impact of Mobilization Regimens and the Influence on Outcomes in Breast Cancer Patients

Abstract

Tumor cell contamination (TCC) of peripheral blood stem cells (PBSCs) is a major risk in the autologous PBSC transplant setting. However, the effect of different mobilization regimens (cytokines only versus cytokines + chemotherapy) on TCC of PBSCs and its impact on treatment outcomes have not been systematically reviewed. In the present meta-analysis, we aimed to investigate this effect in breast cancer patients since multiple studies have been conducted in this setting. We systematically searched MEDLINE and Cochrane Library up to May 2012. Seventeen studies (1,819 patients) were assessed. There was no significant difference in the incidence of TCC of PBSCs between the two mobilization regimens. When the analysis was restricted to granulocyte colony-stimulating factor as a cytokine, this difference was again not significant. We also found that TCC of PBSCs was associated with a higher annual recurrence rate in these patients. This suggests that there may be a significant risk for reinfusion of tumor cell-positive PBSCs, and whether it can increase the risk of disease recurrence needs to be determined. This study also raises important questions regarding the causes of TCC of PBSCs. These issues should be investigated systematically in PBSC transplant patients.

Patients' outcome after rescue plerixafor administration for autologous stem cell mobilization: a single‐center retrospective analysis

“…Potential tumor cell contamination has always been a concern in the process of autologous stem cell mobilization and transplantation although the impact of contaminating tumor cells on patients' prognosis is controversial and might be dependent on the underlying malignant disease . With respect to the myeloma patients included into our study, we did not observe an enhanced frequency of cells with malignant phenotype in the apheresis products in patients mobilized with G‐CSF and plerixafor further emphasizing the safety of this mobilization procedure.…”

Efficacy of plerixafor in children with malignant tumors failing to mobilize a sufficient number of hematopoietic progenitors with G-CSF

“…Although one large meta-analysis found no differences in malignant contamination between apheresis products mobilized with chemotherapy plus G-CSF and those mobilized with G-CSF alone, 19 these data cannot be directly extrapolated to plerixafor plus G-CSF regimens, as the mechanism of disruption of the cell-stroma interaction is different with plerixafor. This issue should be studied further, and posttransplantation relapse rates should be analyzed.…”

The ex vivo purge of cancer cells using oncolytic viruses: recent advances and clinical implications

“…Tumor cell loads between a few malignant cells per 100,000 nucleated blood cells to several percent of the cells in a graft product have been reported. 9 , 10 Some clinical studies have shown a correlation between reinfusion of grafts containing residual cancer cells and higher rates of relapse. 11 , 12 For instance, in a Phase II clinical trial of autologous bone marrow transplantation for non-Hodgkin’s lymphoma, patients whose grafts were free of lymphoma cells, as determined by polymerase chain reaction (PCR) for the B-cell lymphoma 2 ( Bcl2 ) translocation, had significantly longer relapse-free survival when compared to the survival of patients with detectable lymphoma cells.…”