Relationship of tumor load parameters before and after autologous stem cell transplantation with clinical prognosis in transplant-eligible patients with multiple myeloma: A retrospective analysis.

We retrospectively examined 57 patients with multiple myeloma who underwent autologous stem cell transplantation (ASCT) at our institution. A receiver-operating characteristic curve (ROC) analysis showed that the reduction rate of quantitative serum monoclonal protein (M-protein) before ASCT and the difference in involved and uninvolved free light chains (dFLC) 30 days after ASCT, respectively, had the greatest predictive value for all patients (area under the curve [AUC] 0.791 and 0.660, respectively). Based on the ROC curve-based cutoff values of tumor burden parameters, progression-free survival (PFS) in the high serum M-protein reduction (≥90 %) group was significantly better than that in the low serum M-protein reduction group (<90 %) (2-year PFS 79.5 % vs. 17.0 %, p < 0.001), but there were no significant differences in PFS between the low (<5.2 mg/L) and high (≥5.2 mg/L) dFLC groups (2-year PFS, 72.0 % vs. 46.0 %; p = 0.149). A multivariate analysis identified the reduction in serum M-protein as an independent predictive factor before ASCT for PFS (hazard ratio [HR] 0.287, p = 0.022) and high dFLC on day 30 after ASCT for PFS (HR 3.902, p = 0.040). These results demonstrate that a good prognosis can be expected with a reduction of serum M-protein before and after ASCT.