Paris - An investigation into stored umbilical cord blood has given a significant boost to using this novel material for children struck by leukaemia.
The mainstream approach for treating leukaemia - cancer of the blood - is to find a donor, typically a sibling, whose bone marrow is a genetic match of the recipient.
But this lucky match only occurs in less than one-in-three cases.
That usually leaves doctors hunting for compatible bone marrow from an adult donor and, even if they find it, such transplants are vulnerable to transmitted disease and opportunistic infection.
Recently another possibility has emerged: using stored umbilical cord blood, which is rich in primitive stem cells that form the different types of blood cell.
However, this blood, frozen and stored by parental consent after a baby is born, also has an obstacle in the form of two antigens, which if mismatched may trigger an immune response against the transplant.
A new study, though, suggests that this mismatch may be less of a problem than thought.
Researchers led by University of Minnesota haematologist John Wagner studied 503 children under 16 years who were treated for acute leukaemia using umbilical blood, and compared their outcomes with 282 children who had received bone marrow.
The good news: the survival rate among those who received umbilical cord blood that was unmatched for one or both antigens was as good as the group that received matched bone marrow.
But researchers also discovered that the death rate was twice as high among children who received umbilical blood with two mismatched antigens, regardless of the size of the transplant.
Among those who received one mismatched antigen, mortality was lower if the transplant dose was higher.
The study, which is published in The Lancet on Saturday, gives an important additional treatment option for physicians who until now may have balked at the idea of using mismatched cord blood for childhood leukaemia.
Matched umbilical blood appears to offer a better chance of survival over matched bone marrow, although the number of children studied was small and further work is needed to confirm this.
The authors call for greater investment in umbilical cord blood banks and in improving procedures to identify antigen matches.