High-dose chemotherapy and autologous stem cell transplantation as treatment for high-risk breast cancer

High-dose chemotherapy with autologous stem cell transplantation has emerged as a common treatment for patients with breast cancer who have a poor prognosis. The success of this approach appears to depend on the tumor burden and the sensitivity of the disease to chemotherapy because treatment techniques have been refined and treatment-related mortality has declined. Phase II studies in patients with stage II and III disease are encouraging and suggest that treatment with high-dose chemotherapy before the development of metastatic disease may provide an advantage in terms of relapse-free and overall survival. However, tumor cells may contaminate stem cell collections and contribute to relapse after transplantation. Therefore it may be important to separate and select purified CD34⁺ cells which are not contaminated. It has been suggested that selection bias contributes to the favorable preliminary results observed in phase II studies of high-risk patients. Such issues,together with patient and physician bias regarding the benefits of this strategy, emphasize the need to complete the prospective randomized trials now underway.