Unrelated cord blood transplantation vs matched unrelated donor bone marrow transplantation: the risks and benefits of each choice.

Matched sibling BMT is the treatment of choice for many malignant and non-malignant diseases. Unfortunately, donor availability limits its applicability with only approximately one-third of patients having HLA-matched family members. For the remaining two-thirds of patients who need an allogeneic procedure, an alternative donor is required. Matched unrelated donor (MUD) bone marrow transplants have proven useful for many of these patients, however, matched donors may be unavailable or too time-consuming to find. In addition, MUD transplants are associated with high morbidity and mortality secondary to severe graft-versus-host disease (GVHD), organ toxicity, and infections. For those patients without a matched related or unrelated volunteer donor, unrelated umbilical cord blood transplantation (UCBT) is a feasible alternative. UCBT has been associated with a lower incidence and severity of GVHD than MUD BMT, allowing successful transplantation in the HLA-mismatched setting, thus increasing the donor pool. This manuscript reviews the available literature regarding these two procedures, assesses their risk/benefit ratio, and arrives at several conclusions regarding their relative indications.