Effect of the Amount of Autologous Hematopoietic Stem Cells on Survival and Engraftment in Multiple Myeloma
Background: Autologous stem cell transplantation (ASCT) is currently a gold standard treatment for eligible multiple myeloma (MM) patients. The recommended dose of CD34+ hematopoietic progenitor cells (HPCs) for adequate engraftment is above 2 × 106 cells/kg. Objectives: This study aimed to evaluate the relationship between the number of CD34+ HPCs and the survival in MM patients who underwent ASCT in the Hematology Department of Abdurrahman Yurtaslan Ankara Oncology Training and Research Hospital, Ankara, Turkey. Materials and Methods: The statistical population of this consisted of 200 MM patients who underwent ASCT within 2009-2019. The clinical characteristics of the patients, disease status pre-SCT, number of infused CD34+ cells, neutrophil, and platelet engraftment days were recorded. The patients were divided into two groups, based on whether the re-infused CD34+ HPCs dose was < 5 × 106 cells/kg (Group 1) or ≥ 5 × 106 cells/kg (Group 2). The groups were compared in terms of engraftment and overall survival (OS) times. Results: A total of 200 patients were included in our study. Group 1 (n=125) included patients with < 5 × 106 cells/kg CD34+ HPC re-infusion, and Group 2 (n=75) consisted of patients with ≥ 5 × 106cells/kg CD34+ HPC re-infusion. The patients’ median age scores in Group 1 and Group 2 were 57 (25-71) and 56 (33-72) years, respectively. The median follow-up period was 33 months (6-130). The median OS of all patients was 71 months (95% confidence interval, 59.1-82.9). The median neutrophil and platelet engraftment times were similar between the groups (P=0.4 and P=0.4, respectively). In both groups, the median OS time was 71 months (P=0.8), which was similar. Conclusion: The greater number of CD34+ HPCs re-infusion for ASCT after high dose melphalan chemotherapy in MM patients did not affect platelet and neutrophil engraftment time and OS; therefore, this amount of reinfusion was not required.