Impact of bone marrow plasma cells percentage on survival at diagnosis and pre-transplant period in newly diagnosed multiple myeloma: Experience of a single center from Turkey

Background and aim: The current definition of complete remission (CR) in multiple myeloma (MM) includes negative serum and urine immunofixation (IFE) tests and <5% bone marrow plasma cells (BMPCs). The aim of this study was to examine the impact of BMPC percentage on survival, at diagnosis and pre-transplant period, in newly diagnosed multiple myeloma. Materials and methods: One hundred and fourty eight patients with newly diagnosed MM who had received autologous stem cell transplantation (ASCT) in our HSCT (hematopoietic stem cell transplant) center at Hacettepe University Hospital between the years of 2008 and 2018 were evaluated retrospectively. Results: The median follow-up period was 27.4 months (range, 4.5–122) for the entire group. The 3-year OS was 87% in the pre-transplant BMPCs <5% group and 92% in the pre-transplant BMPCs ≥ 5% group, there was no statistically significant difference. The 5-year OS for the pre-transplant BMPCs <5% group and the pre-transplant BMPCs ≥ 5% group were 73% and 70%, respectively (p = 0.50). The 3-year PFS in the pre-transplant BMPCs <5% group and the pre-transplant BMPCs ≥ 5% group were 77% and 57%. The 5-year PFS in the pre-transplant BMPCs <5% group and the pre-transplant BMPCs ≥ 5% group were 43% and 13%, respectively. There was a statistically significant difference between the two groups with respect to PFS (p = 0.04). Conclusion: In conclusion, this study highlights the importance of reaching <5% BMPCs at pre-transplant period. OS and PFS were better in patients who had pre-transplant BMPCs <5% than pre-transplant BMPCs ≥ 5%.