Long term hematologic recovery after autologous stem cell transplantation in lymphoma patients: impact of the number of prefreeze and post-thaw CD34+ cells.

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.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.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.An optimal long-term hematologic recovery after ASCT required a number of prefreeze CD34+ cells of at least 5.10(6)/kg.