Transplants of peripheral blood cells may be more effective than bone marrow transplants in patients who receive high-dose chemotherapy for blood cancer, according to a large randomized trial reported in the New England Journal of Medicine on 18 January 2001.
Physicians use both kinds of transplants in blood cancers such as leukemia and lymphoma, primarily to restore bone marrow destroyed by high-dose chemotherapy. In this study, the transplanted peripheral blood cells took effect more quickly than the marrow transplants, without increasing the risk of complications.
Led by William Bensinger, M.D., at the Fred Hutchinson Cancer Research Center in Seattle, Wash., the researchers compared the two kinds of transplants in 172 patients from between 12 and 55 years of age. Patients were randomly assigned to two groups, one to receive the marrow transplants and the other to received the peripheral blood cells. Both transplants were allogeneic came from relatives and were given after high doses of chemotherapy with or without radiation therapy.
One of the major goals of the trial was to compare the two groups in terms of risk of graft-versus-host disease (GVHD), a common and sometimes fatal complication of allogeneic transplants in which the patients immune system attacks the transplant. Other studies have suggested GVHD may be more common among patients who receive peripheral blood cell transplants. However, in this trial, rates of GVHD in the two groups were not significantly different. Chronic, extensive GVHD occurred in 37 of the peripheral blood cell patients and in 32 of those who received bone marrow transplants.
The patients in the trial who received peripheral blood cells recovered from the effects of the high-dose chemotherapy more quickly than those who received bone marrow transplants. Their blood counts -- the numbers of white blood cells and platelets -- returned to normal levels five or six days faster and they required fewer transfusions of platelets.
The trial results also suggested that peripheral-blood stem cell transplants may result in better survival rates among patients with advanced blood cancers. At two years, about 66 percent of these patients were alive compared with 54 percent in the bone marrow group. In the subgroup of patients with more advanced cancers, survival at two years was about 57 percent in the peripheral blood group versus 33 percent in the bone marrow group. There was also some evidence of a lower risk of relapse in the peripheral blood group.
In their discussion of these findings, the authors point out that they did not design the study to show whether survival rates were better and therefore, "these results must be interpreted with caution." Their principal conclusion is that allogeneic peripheral-blood cells restore blood counts faster than allogeneic bone marrow, without increasing the risk of graft-versus-host disease.