Impact of selection process on response rate and long-term survival of potential high-dose chemotherapy candidates treated with standard-dose doxorubicin-containing chemotherapy in patients with metastatic breast cancer

Purpose: Most of the data about high-dose chemotherapy (HDCT) for metastatic breast cancer are derived from phase H studies. The interpretation of these data depends on comparisons with data from properly selected historical control patients treated with standard therapy under similar circumstances. We report the long-term results of patients with metastatic breast cancer who were eligible far HDCT but were treated with doxorubicin- containing standard-dose chemotherapy. Patients and Methods: Prospectively collected data from 18 successive doxorubicin-containing protocols for the treatment of metastatic breast cancer were evaluated. Using common eligibility criteria for HDCT, we identified patients who would have been candidates for HDCT. We analyzed response rates, progression-free survival (PFS), and overall survival (OS) for all patients, potential HDCT candidates, and noncandidates. Results: A total of 1,581 patients was enrolled onto the 18 studies. Six hundred forty-five were HDCT candidates, and 936 were noncandidates. The complete response rate was 27% for HDCT candidates and 7% for noncandidates; median PFS was 16 and 8 months and median OS was 30 and 17 months, respectively. Survival rates for HDCT candidates and noncandidates, respectively, were 21% and 6% at 5 years and 7% and 2% at 10 years. Conclusion: This study suggests that encouraging results of single-arm trials of HDCT could partially be due to selection of patients with better prognoses and further stresses the importance of completing ongoing randomized trials of HDCT to assess the relative efficacy of HDCT in patients with metastatic breast cancer.