Doxorubicin and Paclitaxel Versus Doxorubicin and Cyclophosphamide as First-Line Chemotherapy in Metastatic Breast Cancer: The European Organization for Research and Treatment of Cancer 10961 Multicenter Phase III Trial

Abstract

PURPOSE: To compare the efficacy and tolerability of the combination of doxorubicin and paclitaxel (AT) with a standard doxorubicin and cyclophosphamide (AC) regimen as first-line chemotherapy for metastatic breast cancer. PATIENTS AND METHODS: Eligible patients were anthracycline-naive and had bidimensionally measurable metastatic breast cancer. Two hundred seventy-five patients were randomly assigned to be treated with AT (doxorubicin 60 mg/m2 as an intravenous bolus plus paclitaxel 175 mg/m2 as a 3-hour infusion) or AC (doxorubicin 60 mg/m2 plus cyclophosphamide 600 mg/m2) every 3 weeks for a maximum of six cycles. A paclitaxel (200 mg/m2) and cyclophosphamide (750 mg/m2) dose escalation was planned at cycle 2 if no grade ≥ 3 neutropenia occurred in cycle 1. The primary efficacy end point was progression-free survival (PFS). Secondary end points were response rate (RR), safety, overall survival (OS), and quality of life. RESULTS: A median number of six cycles were delivered in the two treatment arms. The relative dose-intensity and delivered cumulative dose of doxorubicin were lower in the AT arm. Dose escalation was only possible in 17% and 20% of the AT and AC patients, respectively. Median PFS was 6 months in the two treatments arms. RR was 58% versus 54%, and median OS was 20.6 versus 20.5 months in the AT and AC arms, respectively. The AT regimen was characterized by a higher incidence of febrile neutropenia, 32% versus 9% in the AC arm. CONCLUSION: No differences in the efficacy study end points were observed between the two treatment arms. Treatment-related toxicity compromised doxorubicin-delivered dose-intensity in the paclitaxel-based regimen