In the largest multi-center study ever researchers found the use of allogeneic peripheral blood stem-cells for transplantation significantly increased the tempo of cell production, compared to marrow. Suggesting that disease-free survival may be significantly improved for patients. The results of the study are reported in the Jan. 18 issue of the New England Journal of Medicine.
The study, led by Dr. William Bensinger at the Fred Hutchinson Cancer Research Center in Seattle, involved 172 patients with hematologic malignancies who were treated at the Hutchinson Center, University of Washington, City of Hope and Stanford University. The study compared outcomes of cancer patients two years after undergoing a marrow or stem cell transplant. The study confirmed that for certain patients stem cells offer clear advantages.
The study evaluated the incidence of acute and chronic graft-versus-host disease (GVHD) and the rate of growth of donor cells in patients who underwent a marrow or stem-cell transplant from a matched family member donor between March 1996 and July 1999. Researchers found 45 percent of the patients undergoing marrow transplant and 65 percent undergoing peripheral blood stem-cell transplants were surviving disease free after two years. The incidence of acute GVHD was 57 percent with marrow and 64 with peripheral blood stem cells, while chronic GVHD was lower, with the incidence of 34 percent with marrow and 46 percent with peripheral blood stem cells.
According to researchers, the data offers promising news for many patients with high-risk blood cancers. These include patients with advanced-stage leukemia and those who have suffered one or more relapses as well as patients with lymphomas that did not respond to treatment.
"The evidence is convincing enough that we've already made a change in treating our high risk patients," says Bensinger, also an associate professor at the University of Washington School of Medicine. "For patients with accelerated phases of chronic or acute leukemia, and patients who are beyond first remission or have refractory (nonresponsive) relapses, we are using stem cells."
Bensinger says the advantage of stem cells over marrow transplants for low-risk patients remains less clear because they don't have enough data yet to draw conclusions.
"We think that stem cells may offer an advantage for those patients as well," he says. Physicians consider marrow transplantation as the standard treatment for many cancers of the blood and immune system.
Stem cell transplants use cells collected from the donor's blood, using an outpatient procedure known as apheresis. Blood taken from a donor runs through a machine that extracts the stem cells from the patient's blood and returns the rest to the donor. Marrow cells are harvested from the donor in an operating-room procedure where cells are removed with a syringe from the pelvic bone.
"The results are exciting because most strategies aimed at reducing relapse are associated with higher toxicities, more complications and higher mortality," Bensinger says. "This data suggests that stem cell transplants may offer the best of both worlds, fewer relapses with fewer complications."
Emphasizing that there is still a lot to be understood, Bensinger says there are several reasons to be cautious about the results. Other studies suggest that stem cell patients have higher rates of chronic graft-versus-host disease, which may not occur until three to five years after transplant. In a delayed reaction, the donor immune cells attack the patient's skin, liver, eyes, mouth, esophagus and joints and must be controlled with immune suppression drugs.
"We won't know for another year or two if chronic graft-versus-host disease shows up among these patients," he says.
The Fred Hutchinson Cancer Research Center is an independent, nonprofit research institution dedicated to the development and advancement of biomedical technology to eliminate cancer and other potentially fatal diseases. Recognized internationally for its pioneering work in bone-marrow transplantation, the Center's four scientific divisions collaborate to form a unique environment for conducting basic and applied science. The Hutchinson Center is the only National Cancer Institute-designated comprehensive cancer center in the Pacific Northwest. For more information, visit the Center's Web site at www.fhcrc.org
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