Inclusion of taxanes, particularly weekly paclitaxel, in preoperative chemotherapy improves pathologic complete response rate in estrogen receptor-positive breast cancers

Abstract

We examined if inclusion of a taxane and more prolonged preoperative chemotherapy improves pathologic complete response (pCR) rate in estrogen receptor (ER)-positive breast cancer compared with three to four courses of 5-fluorouracil, doxorubicin, cyclophosphamide (FAC). Pooled analysis of results from seven consecutive neo-adjuvant chemotherapy trials including 1079 patients was carried out. These studies were conducted at MD Anderson Cancer Center from 1974 to 2001. Four hundred and twenty-six (39.5%) patients received taxane-based neo-adjuvant therapy. pCR rates and survival times were analyzed as a function of chemotherapy regimen and ER status. Multivariate logistic and Cox regression analysis were carried out to identify variables associated with pCR and survival. Patients with ER-negative cancer had higher overall pCR rate than patients with ER-positive tumors (20.1% versus 4.9%, P < 0.001). In ER-negative patients, the pCR rates were 29% and 15% with and without a taxane (P < 0.001). In ER-positive patients, the pCR rates were 8.8% and 2.0% with and without a taxane (P < 0.001). In multivariate analysis, clinical tumor size (P < 0.001), ER-negative status (P < 0.001) and inclusion of a taxane (P = 0.01) were independently associated with pCR. For patients with pCR, survival was similar regardless of ER status or the type of regimen that induced pCR. pCR rates increased for patients with both ER-positive and ER-negative tumors as regimens started to include a taxane and became longer. This indicates that a subset of patients with ER-positive breast cancer benefits from more aggressive chemotherapy, similarly to patients with ER-negative tumors.