Breast Cancer: High-Dose Therapy

Breast cancer has become the leading indication for high-dose chemotherapy (HDC) with autologous stem cell rescue (ASCR) in North America. The rapid increase in HDC/ASCR for breast cancer has been driven by belief in the response rates and survival times demonstrated in phase II studies, which have been higher than that of historical controls. However, there is a growing body of data to suggest that selection bias has had a significant impact on the outcome of non-randomized studies of HDC. Few randomized comparisons of HDC to standard-dose chemotherapy exist. Early studies of dose-intensification and phase II studies of HDC/ASCR for patients with metastatic and high-risk disease are reviewed here, with emphasis on those studies with long-term follow-up. Studies demonstrating the selection bias present in phase II studies of HDC are also discussed. Finally, randomized studies of HDC/ASCR are reviewed, including the National Cancer Institute high-priority trials. Currently, HDC/ASCR for the treatment of breast cancer can only be recommended in the context of a clinical trial. Results of several large randomized trials are awaited to determine the future of HDC/ASCR for breast cancer.