Autologous Stem Cell Transplants Taking Breast and Ovarian Cancer Chemotherapy to New Heights.
Traditional chemotherapy regimens for advanced breast cancer have produced complete response (CR) rates of 5%-25% and remissions of 5-13 months. Autologous stem cell transplantation (ASCT), however, permits a 5- to 10-fold escalation of chemotherapy, which results in a substantial increase in tumor-cell killing relative to standard therapy. This technique involves protecting hematopoietic function by collecting stem cells from bone marrow or peripheral blood before subjecting the patient to high-dose chemotherapy. These stem cells are then reinfused in an autologous bone marrow transplant (ABMT) or autologous blood stem cell transplant (ABSCT) to quickly repopulate the patient's marrow and blood. The largest and most mature of phase II trials of ASCT for metastatic breast cancer reports rates of 35%-68% and 4-year survival rates of 19%-27%. Although most patients develop recurrent disease 6-12 months post-ASCT, it is encouraging that a few patients survive, disease-free, beyond 5 years. The Autologous Blood and Marrow Transplant Registry analyzed data on more than 800 patients with metastatic breast cancer who underwent ASCT. The Registry reported a 3-year progression-free survival rate of 20% and an overall survival rate of 37%, which compares favorably with an expected 17%-25% 3-year survival rate after conventional chemotherapy. Whether similar success can be achieved with ASCT in ovarian cancer is uncertain because few ovarian cancer patients are presently entered in high-dose studies using ASCT support.
Stewart
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Department of Medicine at the Tom Baker Cancer Centre, Foothills Hospital, Canada; University of Calgary in Alberta, Canada.