Bone Marrow Transplants a Thing of the Past?
"Our main message is that allogeneic peripheral blood stem cells are an important alternative to marrow as a source of stem cells," says William I. Bensinger, MD, a co-author of the New England Journal of Medicine study. These cells may have certain advantages over marrow in terms of lower rates of complications, death, and disease relapse, adds Bensinger, an associate professor of medicine at the Fred Hutchinson Cancer Research Center in Seattle.
In the study, 172 patients were randomly assigned to receive either bone marrow or peripheral blood stem cells, both from closely matched relatives. The group receiving the blood cells recovered certain important blood components -- the neutrophils and platelets -- significantly faster than the bone marrow group, and they required fewer transfusions of platelets.
A frequent complication of allogeneic transplants is graft-vs.-host disease, where the donor cells attack the patient's organs and tissue. This occurs most often in patients who receive transplants from relatives who weren't a suitable match or from unrelated donors. In this study, the overall rate of graft-vs.-host disease was about the same between the two groups.
At the end of 2 years, 65% of the patients who had received the peripheral blood were alive and free of their disease, which could be said of only 45% of the bone marrow group. Interestingly, the patients who benefited the most from the blood stem cells were those with more advanced disease.
"These results suggest that use of blood stem cell transplants may offer advantages over bone marrow grafts in terms of overall survival and disease-free survival," says Lazarus, "But it remains to be determined whether the use of blood rather than marrow is preferred in subjects in whom the disease is not so advanced."
Also, Lazarus adds, it is uncertain whether these same benefits would be seen when the donor is not as closely matched as the ones in this study were, or if the donor is unrelated.
An advantage to this procedure is that it is safer for the donor, because blood cells can be extracted in an outpatient procedure not requiring an operating room or anesthesia. In turn, this could mean more people would be likely to volunteer as donors, says Lazarus.