Cord-blood transplantation in patients with leukemia--a real alternative for adults.

A steady stream of advances in allogeneic hematopoietic stem-cell transplantation has not only improved the clinical outcome in a variety of malignant and nonmalignant diseases but also widened the indications for such transplants. One important advance is the use of sources of hematopoietic stem cells other than bone marrow from HLA-identical siblings, which is a resource available to only about 30 percent of potential recipients. By searching international databases, which contain more than 9 million potential volunteer stem-cell donors, 1 a matched unrelated donor can be found for an additional 50 to 80 percent of patients, depending on ethnic group. In the United States, however, only 30 percent of whites (and a slightly lower percentage of members of minority populations) for whom a search is initiated ultimately receive a marrow transplant from an unrelated donor. This low proportion is mainly due to deterioration of the patient’s condition or death during the search. 2 For situations in which a matched unrelated donor cannot be found within a reasonable time, umbilical-cord blood has emerged as an attractive source of hematopoietic stem cells. Acceptable cord-blood units can be identified for most patients, because less stringent HLA compatibility with the recipient is required. Another important advantage of cord blood is the rapidity with which an acceptable cord-blood unit, once identified, can be acquired (median interval, 13.5 days). 3