Double vs. single cord blood transplantation in adolescent and adult hematological malignancies with heavier body weight (≥50 kg)

<b>Background</b>: Double-unit cord blood transplantation (CBT) can be used to overcome the limitation of single-unit CBT with low cell content for adults and larger adolescents. However, whether double-unit CBT is superior to single-unit CBT remains controversial. <b>Methods</b>: We reviewed the medical records of 228 consecutive hematological malignancies who received CBT between November 2005 and December 2013. Ninety-seven eligible patients met the criteria (age ≥14 years and body weight ≥50kg) and were enrolled in this study. <b>Results</b>: The incidence of myeloid engraftment in the double-unit CBT group was significantly lower that in the single-unit CBT group (89.2 vs. 96.7%) (<i>p</i> = 0.026), and the incidence of platelet engraftment in the double-unit CBT group was slightly lower (70.3 vs. 86.7%) (<i>p</i> = 0.057). The 5-year transplant-related mortality rate was significantly higher in the double-unit CBT group when compared with that of the single-unit CBT group [54.1 vs. 33.3%, <i>p</i> = 0.026]. The 5-year probabilities of overall survival, disease-free survival and graft-versus-host disease (GVHD) -free/relapse-free survival in the double-unit CBT group were significantly lower than that of the single-unit CBT group (37.8 vs. 56.7%, <i>p</i> = 0.037; 32.4 vs. 55.0%, <i>p</i> = 0.017; 24.3 vs. 50.0%, <i>p</i> = 0.006). The incidences of GVHD and relapse were similar. <b>Conclusions</b>: For adolescent and adult hematological malignancies with heavier body weight (≥50kg), double-unit CBT has an inferior clinical outcome when compared with single-unit CBT having a sufficient cell dose. Double-unit CBT should only reserve for patients who need an urgent transplant but lacking of a related or unrelated donor and without an adequately dosed single CB.