Favorable Long-Term Outcomes with Autologous Stem Cell Transplantation for High-Risk Multiple Myeloma Patients with a Positive Result On ¹⁸F-FDG PET/CT at Baseline

Background: 18F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) is a useful tool for identifying high-risk features in patients with newly diagnosed multiple myeloma (NDMM). This study evaluated the role of autologous stem cell transplantation (ASCT) in patients presenting with positive results on PET/CT scans. Materials and Methods: The medical records of 210 patients who underwent PET/CT at diagnosis were retrospectively reviewed. Eligible patients for transplantation proceeded to upfront ASCT with high-dose chemotherapy (HDT) after induction therapy with novel agents. Results: The presence of a number of focal lesions (FL) >3 and extramedullary disease (EMD) occurred in 111 and 35 patients, respectively. ASCT was performed in 54 patients. Among patients with FL > 3, those treated with ASCT showed a prolonged 2-year progression-free survival (PFS) and overall survival (OS) rates compared to those not treated with ASCT (PFS, 60.2% vs. 23.5%, P < 0.001; OS, 91.7% vs. 63.6%, P = 0.005). In patients with FL ≤ 3, treatment by ASCT was associated with a higher 2-year PFS rate than no treatment by ASCT (74.0% vs. 54.9%, P = 0.040). The OS of patients treated with ASCT was not significantly longer than that of patients not treated with ASCT (P = 0.115). In multivariate analysis, FL > 3, Revised International Staging System (R-ISS), and upfront ASCT were independent prognostic factors for PFS and OS. Conclusion: Presenting FL > 3 on baseline PET/CT represents a high-risk feature in patients with NDMM. Frontline ASCT with HDT prolonged the survival of patients with FL > 3.