Phase III study of doxorubicin-cyclophosphamide followed by paclitaxel or docetaxel given every 3 weeks or weekly in operable breast cancer: Results of Intergroup Trial E1199

Abstract

516 Background: Evidence suggests that docetaxel is more effective than paclitaxel, and paclitaxel is more effective when given weekly than every 3 weeks in metastatic breast cancer (BC). Methods: Eligibility included axillary lymph node positive or high-risk (tumor at least 2 cm) node-negative BC. All patients received 4 cycles of AC (doxorubicin 60 mg/m2 and cyclophosphamide 600 mg/m2) every 3 weeks, followed by either: (1) paclitaxel 175 mg/m2 every 3 weeks × 4 (P3), (2) paclitaxel 80 mg/m2 weekly × 12 (P1), (3) docetaxel 100 mg/m2 every 3 weeks × 4 (D3), or (4) docetaxel 35 mg/m2 weekly × 12 (D1). The primary comparisons included taxane (P vs. D) and schedule (every 3 weeks vs. weekly), and secondary comparisons included P3 vs. other arms. The trial had 86% power to detect a 17.5% decrease in disease-free survival (DFS) for either primary comparison, and 80% power to detect a 22% decrease for the secondary comparisons (2-sided nomimal 5% level tests corrected for multiple comparisons). Results: A total of 4,950 eligible patients were accrued. There was no difference in the primary comparisons afer 856 DFS events and 483 deaths after a median follow-up of 46.5 months at the 4th interim analysis ( www.sabcs.org , abstract 48). This is the final pre-specified analysis for the primary comparisons after 1,042 DFS events and 650 deaths (with 1,020 DFS events at this time, to be updated at the meeting). After a median followup of 60.2 months, there remains no significant difference in the hazard ratio (HR) for the taxane (1.02; p=0.73) or schedule (1.07; p=0.30) (as in the first analysis). In secondary comparisons of the standard arm (P3) with the other arms (HR > 1 favoring the experimental arms), the HRs were 1.30 (p = 0.003) for arm P1, 1.24 (p=0.02) for arm D3, and 1.09 (p=0.33) for arm D1. Analysis of interaction by hormone-receptor status will be presented. The incidence of worst grade toxicity (grade 3/4) was 24%/6% for arm P3, 24%/3% for arm P1, 21%/50% for arm D3, and 38%/6% for arm D1. Conclusions: There were no differences in DFS when comparing taxane or schedule overall. DFS was significantly improved in the weekly paclitaxel and every 3-week docetaxel arms compared with the every 3-week paclitaxel arm. [Table: see text]