Weekly paclitaxel improved pathologic response of primary chemotherapy compared with standard 3 weeks schedule in primary breast cancer

The purpose of this study is to compare the efficacy of weekly paclitaxel to every-3-week schedule in terms of pathologic response and toxicity which caused treatment delay in primary chemotherapy of breast cancer. After pretreatment of two cycles of cyclophosphamide/ pirarubicin/ fluorouracil (cyclophosphamide 500 mg/m² days 1, 8; pirarubicin 35 mg/m² days 1, 8; 5-Fu 200 mg/m² day ci day 1–28, every 4 weeks), 219 women with histologically confirmed T_1–3 N_0–2 M₀ invasive breast cancer, whose vertical diameters production of breast tumor reduced not more than 75%, were randomized to receive four cycles of Pq3wC (arm A: paclitaxel 175 mg/m² day 1, carboplatin AUC 6 d1, every 3 weeks) or Pq1wC (arm B: paclitaxel 60 mg/m²  days 1, 8, 15, carboplatin AUC 6 day 1 for every 3 weeks) before surgery, stratified by partial or no response (stable disease and progression of disease) evaluated by ultrasonography. Pathologic response of the primary tumor was assessed by using Miller and Payne grading system. We defined grade 4/5 as excellent response, grade 3/4/5 as response and treatment delay as paclitaxel administration being delayed at least 1 week because of toxicity in this study. 213 patients (2 cases with concurrent bilateral breast cancer) were eligible for analysis, 109 patients with 110 lesions in arm A and 104 patients with 105 lesions in arm B. Patients in arm B had a higher excellent pathologic response rate and a higher pathologic response rate compared with patients in arm A (59.0 vs. 45.5%, P = 0.046 and 86.7 vs. 71.8%, P = 0.007). Pathologic complete response (pCR) rate in breast alone was similar between two arms (P = 0.733), but there was a higher pCR rate in patients with partial response to two cycles of cyclophosphamide/pirarubicin/fluorouracil than those with no response (32.4 vs. 13.9%, P = 0.001). There was no treatment-related death, however more patients in arm B than in arm A experienced treatment delay caused by toxicity (60.6 vs. 11.9%, P < 0.001). Under the condition of same cumulative doses, weekly paclitaxel was more effective than 3 weeks schedule in terms of pathologic response to primary chemotherapy in breast cancer, and caused more treatment delay related to toxicity though well tolerant.