Leukemia patients often undergo radiation or chemotherapy to kill their cancerous white blood cells -- a treatment that wipes out their immune systems, too. To restore their immune systems, doctors give these patients an infusion of bone marrow or umbilical cord blood, both of which contain stem cells capable of developing into every kind of blood cell.
Cord blood offers an important advantage over marrow that makes it particularly valuable for use in transplants: Its stem cells are less likely to attack the recipient's body. That allows a wider margin of error in matching up donors and recipients.
But up to now, cord blood has been considered suitable only for children, because each donation has only about one-tenth the number of stem cells in a marrow donation.
The two new studies, published yesterday in the New England Journal of Medicine, suggest that is not a serious impediment.
In the European study, involving 682 patients, about one-third of both those who got matched marrow and those who got cord blood that did not quite match their own tissues were alive after two years. In the US study of 601 patients, about one-third of those who got matched marrow were leukemia-free after two years, compared with about one-fifth of those who got cord blood or unmatched marrow.
Both studies were based on records from transplants in the late 1990s and early 2000s.
Using cord blood could improve the odds of getting a transplant for the 16,000 adult leukemia patients in the United States each year who cannot find a compatible marrow donor, said the US study's leader, Dr. Mary J. Laughlin of Case Comprehensive Cancer Center in Cleveland.
Still, Dr. Nancy Kernan, assistant chief of marrow transplantation at Memorial-Sloan-Kettering Cancer Center in New York, said cord blood transplants in adults should be done only as part of studies to look at and improve their effectiveness.
