First analysis of SWOG S0221: A phase III trial comparing chemotherapy schedules in high-risk early breast cancer.

1004 Background: AC+G (doxorubicin 24 mg/m2/week x 15, cyclophosphamide 60 mg/m2/day po, and filgrastim daily except on the days of doxorubicin administration) produced encouraging results in a SWOG Phase II trial of pre-operative chemotherapy in locally advanced breast cancer. S0221 is a SWOG-coordinated Phase III adjuvant chemotherapy intergroup trial in node-positive and high-risk node-negative operable breast cancer, which hypothesized that the AC+G regimen is superior to ddAC (doxorubicin 60 mg/m2, cyclophosphamide 600 mg/m2 IV and pegfilgrastim q 2 weeks x 6) and that weekly paclitaxel is superior to q 2 week paclitaxel. Methods: Between December 2003 and November 2010, 2716 patients were randomized in a 2x2 factorial design to 1) AC+G vs ddAC and 2) paclitaxel 80 mg/m2/week x 12 vs paclitaxel 175 mg/m2 q 2 weeks x 6. If there was no significant interaction between the factors, the trial was powered to find a disease-free survival hazard ratio (HR) ≤ 0.82 for weekly vs q 2 week for each factor. Resu...