Transplants of umbilical cord blood are as effective as bone marrow transplants at saving the lives of childhood leukemia victims and others whose ravaged immune systems must be restored, a study found.
That's an encouraging finding, because most patients awaiting a bone marrow transplant die before genetically matched marrow can be found.
Using umbilical cord blood instead offers patients another option. More important, umbilical cord blood appears more likely than marrow to work when the donor and the recipient are unrelated. But more research is needed to confirm that.
The new findings "hopefully will go a long way toward convincing people that there is a place for cord blood transplants," said Dr. Joel A. Brochstein, director of pediatric stem cell transplants at Hackensack University Medical Center in New Jersey.
The study the first large comparison of cord blood vs. marrow was reported in today's New England Journal of Medicine. It was conducted the International Bone Marrow Transplant Registry at Medical College of Wisconsin and the Paris-based Eurocord-Cord Blood Transplant Group.
It found that cord blood is less likely to work, but also less apt to trigger a potentially fatal complication called graft versus host disease. The disease happens when the new tissue attacks the recipients' body. It kills up to 40 percent of patients.
In the study, recipients of cord blood and marrow had about the same five-year survival rate: 50 percent for those with malignant diseases and 85 percent for those with nonmalignant diseases.
"We can't say that cord blood is better, but it appears to produce the same survival," said Dr. Mary Horowitz, scientific director of the Milwaukee-based registry.
The transplants didn't "take" among 11 percent of those getting cord blood and 2 percent of those receiving marrow. But patients getting cord blood were only about 40 percent as likely as those getting marrow to develop graft versus host disease.
"It's a wash," Horowitz said.
She said cord blood transplants are probably less likely to work because they provide only one-tenth the cells marrow transplants do.
The study of patients 15 or younger examined the medical records of 113 who had received cord blood and 2,052 who got marrow, each from a sibling with the same tissue type.
The children's immune systems had been wiped out by chemotherapy or radiation given for leukemia, or by genetic blood disorders.
Both cord blood and marrow are rich in stem cells, which are "immature" cells that turn into platelets, red blood cells and infection-fighting white blood cells.
Scientists believe cord blood cells are less likely to attack the recipient because they are young and "more forgiving," and because during pregnancy they learned to tolerate the mother's immune system.
Cord blood has other advantages: There is less chance it is carrying infectious agents, there is no infection risk to a donor, and once it is saved, cord blood is available whenever needed. Marrow donors must undergo painful marrow removal in a hospital.
On the 'Net: New England Journal of Medicine:www.nejm.com