Jan. 17, 2001 -- Although still considered risky, bone marrow transplantation has become one of the standard treatments for a number of serious illnesses, including cancer. But new research suggests another kind of transplant -- using blood cells rather than bone marrow -- might be even more effective for patients suffering from cancers that affect the blood and lymph nodes.
When patients undergo chemotherapy and/or radiation treatment to wipe out their cancer, their healthy cells and bone marrow are often damaged in the process. Doctors then transplant these patients with bone marrow containing healthy stem cells, with the hope that some of them will produce more stem cells while others will grow into mature blood cells.
Although most stem cells are found in the bone marrow, some -- known as peripheral blood stem cells -- are found in the blood. In the Jan. 18 issue of TheNew England Journal of Medicine, researchers report that cancer patients who receive peripheral blood cells do better than those who get bone marrow stem cells.
The patients included in the New England Journal of Medicine study received allogeneic transplants -- that is, transplants donated by another person, in this case, a closely matched relative. Transplants can also be autologous, which is when cells are taken from the patient and stored, and then given back to the patient after chemotherapy.
"In the past decade, the investigators performing autologous stem cell transplants have switched to the use of peripheral blood as the preferred source of stem cells," says Hillard M. Lazarus, MD, professor of medicine at Case Western Reserve University in Cleveland and chairman of the blood and marrow transplant committee of the Eastern Cooperative Oncology Group, one of the largest clinical cancer research organizations in the U.S.
What researchers have found, Lazarus says, is that the bone marrow of patients grows back faster when they get their own blood stem cells than it does when they get their own marrow cells. This leads to fewer treatment-related deaths, shorter hospital stays, and oftentimes, lower costs.
Similarly, reports in recent years have shown allogeneic blood stem cell transplants to be superior to allogeneic bone marrow transplants, says Lazarus, who was not involved in the study but reviewed it for WebMD.
"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.
The results of this study are important for two reasons, says Georgia Vogelsang, MD, an associate professor of oncology at the Johns Hopkins University School of Medicine in Baltimore.
"First, it is a large study from major transplant centers conducting a randomized study," she says. "Prior studies have suffered from small numbers and were generally from a single center."
And second, it opens the door to the next generation of studies, which may utilize better strategies in obtaining stem cells from blood, she says, thereby allowing for better control of graft-vs.-host disease, infection, and relapse. Vogelsang was not involved in the study.
But although these results are promising, it is still uncertain whether stem cells derived from blood are best for everyone.
"Whether or not it should be used over marrow is an issue that should be discussed with a patient's individual physician," says Bensinger.