Good response to paclitaxel predicts high rates of pathologic complete response for breast cancer patients treated preoperatively with paclitaxel followed by 5-fluorouracil, epirubicin and cyclophosphamide.

Objective: Predictors of pathologic complete response (pCR) to neoadjuvant chemotherapy for breast cancers have been studied extensively. Here, we focused on reduction rate after paclitaxel administration for prediction of pCR to paclitaxel followed by 5-fluorouracil, epirubicin, and cyclophosphamide (FEC).

Methods: This study included 115 patients with tumors > or =3.0 cm or with node-positive disease who were treated preoperatively with paclitaxel (80 mg/m(2), once a week, 12 cycles) followed by FEC (500/75/500 mg/m(2), every three weeks, 4 cycles). Reduction rate was measured with magnetic resonance imaging.

Results: Tumor size (< or =5.0 cm) (p = 0.014), estrogen receptor (ER) negativity (p = 0.013), and human epidermal growth factor receptor 2 positivity (p = 0.020), but not histologic type, histologic grade, or progesterone receptor, were significantly associated with pCR, while association of reduction rate > or =80% was highly significant (p = 0.0003). Multivariate analysis identified negative ER (p = 0.022) and reduction rate (p = 0.003) as independent predictors of pCR. Finally, patients with reduction rate > or =80% showed a significantly higher favorable outcome (p = 0.014) than others.

Conclusions: Good response (reduction rate > or =80%) to paclitaxel seems to be a clinically useful predictor of pCR as well as a favorable prognosticator for patients treated preoperatively with paclitaxel followed by FEC.