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342 Chapter 6: Breast Cancer
conclude that high-dose therapy is associated with durable remissions in patients
with high-risk breast cancer and that prognostic factors are useful for identifying
candidates for this therapy.
INTRODUCTION
Since 1992, breast cancer has been the most common indication for high-dose
chemotherapy and autologous stem cell transplantation in North America. 1
In
1997, the Autologous Blood and Marrow Transplant Registry reported outcomes
for >5800 women who had received such therapy. 1
Despite the large number of
women receiving this therapy, the appropriate use of high-dose chemotherapy for
the treatment of breast cancer remains controversial. The available data are
generally based on small series of phase I and II trials rather than on the results of
large, prospective clinical trials. In metastatic breast cancer, for example, there is
only one published prospective, randomized trial comparing high-dose
chemotherapy to standard chemotherapy. 2
Although this trial demonstrates a
superior outcome for patients treated on the high-dose chemotherapy arm, the study
has been criticized due to its small size as well as for the treatment regimen and
associated clinical outcomes seen in the standard therapy arm. In early stage, highrisk
breast cancer, however, two randomized studies have been published
comparing standard chemotherapy to high dose chemotherapy, both of which fail
to demonstrate an advantage for high-dose chemotherapy. 3
- 4
Yet, criticisms can be
raised again for the relatively small number of patients enrolled in each trial, a fact
that limits the statistical power to detect a difference between standard and highdose
therapy. Without the results of large prospective, randomized trials, the
application of high-dose chemotherapy in the treatment of breast cancer will
continue to be debated.
Despite these limitations, a large amount of data is currently available
concerning clinical outcomes following high-dose chemotherapy. The Autologous
Blood and Marrow Transplant Registry has performed multivariate analyses of
patients with breast cancer treated in the adjuvant setting as well as patients
receiving high-dose therapy for the treatment of metastatic disease. 56
At our own
center, we have treated >500 patients with breast cancer in a series of phase I and
II trials of high-dose chemotherapy and autologous stem cell transplantation.
Analysis of clinical outcomes following these clinical trials can be useful in
defining prognostic factors helpful in identifying patients likely to benefit from
high-dose chemotherapy. In this chapter, we present the results of these clinical
trials and describe the pre- and posttransplant factors that influence outcome after
high-dose chemotherapy.