Abstract
BACKGROUND: The optimal role of allogeneic hematopoietic stem cell transplantation (allo-SCT) in multiple myeloma (MM) remains uncertain particularly in the context of modern induction regimens and emerging immune-based therapies. We compared long-term outcomes of allo-SCT versus autologous SCT (ASCT) in a large single-center cohort. METHODS: In this retrospective study, conducted at a single center, 1,342 MM patients underwent transplantation between 1992 and 2022 (1,226 ASCT; 116 allo-SCT), with inherent differences in age and transplant eligibility between groups. Median follow-up was 101 months. Outcomes included overall survival (OS), progression-free survival (PFS), relapse incidence, and non-relapse mortality (NRM). RESULTS: Ten-year OS was comparable between ASCT and allo-SCT groups (59.2% vs. 64.0%; p = 0.38). However, allo-SCT conferred superior PFS (50.6% vs. 26.0%; p = 0.002), driven by a markedly lower relapse incidence (32.5% vs. 68.7%; p < 0.001). This benefit was offset by higher NRM with allo-SCT (23.4% vs. 12.9%; p < 0.001). Baseline laboratory markers, including elevated LDH and hypoalbuminemia, were associated with relapse and non-relapse mortality, respectively. CONCLUSIONS: Allo-SCT offers durable disease control but is limited by treatment-related toxicity. ASCT remains the standard of care, while allo-SCT should be reserved for selected high-risk patients.