Stem-Cell Transplantation Has Advantages Over Bone Marrow Transplantation For Some Leukemia Patients

NEW ORLEANS, DEC. 4, 1999 -- In the largest study ever to compare outcomes of cancer patients transplanted with marrow versus stem cells, Hutchinson Center researchers have found that for certain patients, stem cells offer clear advantages. Results will be presented at the 41st annual American Society of Hematology meeting Dec. 3-7 in New Orleans, La.

William Bensinger, M.D., researcher in the Fred Hutchinson Cancer Research Center's Clinical Research Division and lead author of the study, says that while still preliminary, the data offers promising news for many patients with high-risk blood cancers. These include patients with advanced-stage leukemias 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. "For patients with accelerated phase CML, or AML and ALL 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. It requires an operating-room procedure to extract marrow from the hipbones of a donor. Stem cell transplants use cells collected from the donor's blood, using an outpatient procedure called 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.

In the three-year, multi-center study, 168 patients with a variety of blood cancers were randomly assigned to receive marrow or stem cell transplants. The two-year survival rate among the marrow transplant patients was 45 percent compared to 70 percent for the stem cell patients.

"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 this study is based on preliminary data, 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-vs.-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.

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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 http://www.fhcrc.org.