Transplant of Peripheral Blood Stem Cells Associated with Faster Blood Recovery
High-dose chemotherapy with stem cell transplantation is an important treatment option for many persons with cancer, especially those with leukemia. Although the transplant procedure comes with risks, it is the best chance for cure for many patients. Researchers continue to study which types of stem cell transplantation are most effective in helping the patients’ blood cells recover after high-dose chemotherapy, and which are associated with the fewest complications. French researchers now report that infusion with stem cells collected from the donor’s peripheral blood may produce a more rapid recovery of blood cells than stem cells collected from the donor’s bone marrow, for persons undergoing an allogeneic stem cell transplantation.
Leukemia is a cancer of the blood and bone marrow. Depending on the type and stage (extent of disease at diagnosis) of leukemia, treatment options may include chemotherapy, radiation therapy, and/or biologic therapy (or immunotherapy) to help the immune system. For some leukemias, the use of high doses of chemotherapy will kill more of the leukemia cells; however, these high doses also damage healthy, normal cells, especially those in the bone marrow. The bone marrow (and circulating blood) contains early blood-forming cells, called
stem cells, which grow and mature into the 3 blood cell types: white blood cells (protect the body from infection), red blood cells (carry oxygen to the tissues), and platelets (help the blood to clot). To help restore the damaged stem cells and accelerate blood production, high-dose chemotherapy is combined with a procedure called a stem cell transplantation.
A stem cell transplantation involves the removal of healthy stem cells, either from the patient before he or she receives the high-dose chemotherapy (called an autologous stem cell transplant) or from a donor, who may or may not be related to the patient (called an allogeneic stem cell transplant). Furthermore, the stem cells may be collected from a number of sites in the body, including the bone marrow and the peripheral blood. The stem cells are then frozen, the patient undergoes high-dose chemotherapy to kill the leukemia cells, and the healthy stem cells are infused into the patient’s body to “rescue” the bone marrow and hasten blood production. One of the risks of an allogeneic stem cell transplantation is the development of a condition called graft-versus-host disease (either acute or chronic) after the procedure. The term “graft” refers to the stem cell infusion, while the term “host” refers to the patient. This is a serious condition that can develop when the patient’s body identifies the new stem cells as foreign, and has difficulty accepting them. A group of French researchers sought to determine whether there would be a difference in how quickly blood cells recovered and how often graft-versus-host disease occurred, depending on whether the transplants involved stem cell taken from the peripheral blood or from the bone marrow.
Doctors in France treated 111 persons with early-stage leukemia. All persons received an allogeneic stem cell transplantation. The results from patients who received stem cells from peripheral blood were compared with those from patients who received stem cells from bone marrow. The findings showed that those in the peripheral blood group experienced recovery of blood cell counts 1 week earlier than those in the bone marrow group, resulting in shorter hospital stays in the first 6 months. There were no differences between the 2 patient groups in the occurrence of acute graft-versus-host disease; however, chronic graft-versus-host disease occurred in 50% of those who received stem cells from peripheral blood, and in only 25% of those who received them from the bone marrow. There was no difference in survival times between the 2 patient groups.
These researchers concluded that allogeneic stem cell transplantation using peripheral blood is superior to that using bone marrow, except for the increased incidence of chronic graft-versus-host disease. They also pointed out that persons who develop chronic graft-versus-host disease have a lower rate of recurrence (return of the cancer), and transplants with peripheral blood stem cells have also been shown to be associated with a lower rate of recurrence than those with bone marrow stem cells. It appears that persons with early-stage leukemia who are undergoing stem cell transplantation should receive stem cells from the peripheral blood; however, further study is needed to confirm this determination. Persons who have early-stage leukemia may wish to speak with their doctor about the risks and benefits of stem cell transplantation, or of participating in a clinical trial in which other new treatments are being studied. Other sources of information on ongoing clinical trials include a comprehensive, easy-to-use service provided by the National Cancer Institute (cancer.gov) and the Clinical Trials section and service offered by CancerConsultants.com (www.411cancer.com). (Journal of Clinical Oncology, Vol 18, No 3, pp 537-546, 2000)
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