One-Unit versus Two-Unit Cord-Blood Transplantation for Hematologic Cancers

The use of two units of cord blood to reconstitute hematopoiesis in transplantation for relapsed hematologic cancers in patients 1 to 21 years of age proved to be no better and was in some ways worse than the standard one-unit transplant. Since 1993, unrelated-donor umbilical-cord blood has been used as the source of hematopoietic stem cells for transplantation in an estimated 30,000 patients with malignant and nonmalignant diseases. 1 As compared with stem-cell grafts from adult donors, cord blood has the advantages of more rapid availability, relative absence of donor attrition, and, after transplantation, a reduced risk of graft-versus-host disease (GVHD) despite donor–recipient HLA disparity. 2 , 3 In addition, less restriction on HLA matching permits greater use of cord blood for members of racial minorities, who are less likely to have a suitably HLA-matched volunteer adult donor. 4 However, the use of cord blood . . .