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Stanford study shows stem cell treatment improves survival of patients with metastatic breast cancer

Treating Stage IV breast cancer patients with high-dose chemotherapy followed by a rescue with their own, specially purified blood stem cells that had been purged of cancer, could significantly increase their chances of survival, according to new research from Stanford.

The long-term study (subscription required) was published online last week in Biology of Blood and Marrow Transplantation and is the first to analyze the long-term outcomes of women who received their own (autologous) stem cells that had undergone this purification process. According to a release:

High-dose chemotherapy is considered to be an aggressive treatment because, in addition to killing cancer cells, it also destroys a patient’s blood forming system. Therefore, such patients need to be rescued with stem cells that can restore blood production, which includes red blood cells, platelets and infection-fighting white blood cells. To increase the proportion of blood-forming stem cells in the bloodstream patients routinely receive drugs that “mobilize” the stem cells out of the bone marrow into the blood. Unfortunately, studies by many groups have shown that cancer cells often stowaway in the blood as well and may cause an eventual relapse.

As a result, in the mid-1990s Stanford researchers headed by professors of medicine Karl Blume, MD, Robert Negrin, MD, and professor of pathology Irving Weissman, MD, wondered if there was a way to overcome this problem. They opted to use antibodies that recognized newly identified markers on the surface of the blood stem cells to purify the stem cells away from regular blood and any roving cancer cells. They then used this purified population of stem cells in 22 women with metastatic breast cancer who enrolled in the trial from December 1996 to February 1998. Then they waited as the years passed.

Last year, Mueller and the research team began to compare the progression-free and overall survival of their experimental group to those of a group of 74 women who received identical chemotherapy treatments between February of 1995 and June of 1999 but who received unmanipulated, mobilized peripheral blood.

Results showed five of the 22 women (23 percent) who received the purified stem cells are still alive and four have no sign of disease. Their median overall survival was 60 months. In comparison, seven of the 74 women (9 percent) who received the untreated cells are living and five have no sign of disease. Their median overall survival was 28 months. While the overall numbers were small, researchers hope the results will spur the medical community to revisit using such aggressive treatment options for patients with metastatic breast cancer.

The Stanford Blood and Marrow Transplant group are currently planning a larger clinical trial of the treatment, although the details are still being finalized.

Previously: Stanford Women’s Cancer Center opens Monday, Partial breast irradiation could sidestep side effects of traditional radiation therapy, New breast cancer finding suggests limiting surgery and Stanford researchers find new marker to identify severe breast cancer cases

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