Are matched-related donors always the best choice? A retrospective study exploring the potential of umbilical cord blood.

Outcomes of allogeneic hematopoietic stem cell transplantation are significantly influenced by conditioning regimens and graft-versus-host disease (GVHD) prophylaxis. Previous studies comparing matched-related donor (MRD) and umbilical cord blood (UCB) transplantation included patients with heterogeneous conditioning regimens and GVHD prophylaxis, potentially obscuring the true effects of donor type. We retrospectively compared outcomes of MRD (n = 1335) and UCB (n = 1097) transplantation performed with conditioning regimens and GVHD prophylaxis considered appropriate for cyclophosphamide/total body irradiation-based transplantation. Multivariable analysis revealed better relapse-free survival (RFS) for UCB than MRD in acute myeloid leukemia (hazard ratio [HR]: 0.80; 95% confidence interval [CI]: 0.65-0.99; P = 0.04) and lymphoma (HR: 0.61; 95% CI: 0.37-0.997; P = 0.04). In contrast, RFS was similar between MRD and UCB in acute lymphoblastic leukemia (HR: 0.97; 95% CI: 0.79-1.18; P = 0.74) and worse for UCB in myelodysplastic syndrome (HR: 1.66; 95% CI: 1.09-2.52; P = 0.01). These findings suggest that, when appropriate regimens are used, UCB may perform more favorably than MRD depending on disease type. Further validation in independent registry studies is warranted.