Long term hematologic recovery after autologous stem cell transplantation in lymphoma patients: impact of the number of prefreeze and post-thaw CD34+ cells
Summary :Background. – Autologous Stem Cell Transplantation (ASCT) with Peripheral Blood Stem Cells is widely used as consolidation in lymphoma patients. The rapidity and stability of cell engraftment correlate with the number of CD34+ cells in the autograft. However, whether CD34+ cells should be quantified before or after cryopreservation remains unclear.
Patients and methods. – Of 173 consecutive patients who underwent ASCT in our department from Nov 1, 1995 to Nov 1, 2000, 133 (78 %) were alive without relapse at one year. We report here the results for 106 patients whose hematologic data were available.
Results. – At one year, the hemoglobin was normal in 47 % of the patients, the leukocytes, in 77 % and the platelets, in 60 %. Only 33 % had a normal blood count. We observed a significant correlation between prefreeze and post-thaw CD34+ cell numbers (r \= 0.77). However, multivariate analysis using the Cox model with smoothing splines to assess the best cut-off point for these numbers demonstrated that the only independent predictive factor for a normal blood count after one year was a prefreeze number of CD34+ cells above 5.10
6/kg.
Conclusion. – An optimal long-term hematologic recovery after ASCT required a number of prefreeze CD34+ cells of at least 5.10
6/kg.
Figure 1 Plot of prefreeze and post-thaw numbers of
CD34+ cells (r = 0.77) in lymphoma patients. Dotted line shows the
perfect correlation.
Figure 2 Engraftment of PBSC in lymphoma patients :
relative risk (RR) of granulocytes > 0.5 G/L according to
prefreeze CD34+ cell number. Spline curve show how the RR changes
with the number of CD34+ cells. Dotted lines show the 95 %
confidence interval. Bold lines show the best cut-off point.
Figure 3 Normal blood counts in lymphoma patients at
one year after ASCT : relative risk (RR) of normal blood count
according to prefreeze CD34+ cell number (A) and post-thaw
CD34+ cell number (B). Spline curves show how the RR changes
with the number of CD34+ cells. Dotted lines shows the 95 %
confidence interval. Bold lines show the best cut-off point.
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