Phase III trial evaluating the addition of paclitaxel to doxorubicin followed by cyclophosphamide, methotrexate, and fluorouracil, as adjuvant or primary systemic therapy: European Cooperative Trial in Operable Breast Cancer.

PURPOSE: To evaluate the addition of paclitaxel to an anthracycline-based adjuvant regimen and to compare this combination with the same regimen given as primary systemic (neoadjuvant) therapy.

PATIENTS AND METHODS: A total of 1,355 women with operable breast cancer were randomly assigned to one of three treatments: surgery followed by adjuvant doxorubicin (75 mg/m(2)) followed by cyclophosphamide, methotrexate, and fluorouracil (CMF; arm A); surgery followed by adjuvant paclitaxel (200 mg/m(2)) plus doxorubicin (60 mg/m(2)), followed by CMF (arm B); or paclitaxel (200 mg/m(2)) plus doxorubicin (60 mg/m(2)) followed by CMF followed by surgery (arm C). The two coprimary objectives were to assess the effects on relapse-free survival (RFS) of the addition of paclitaxel to postoperative chemotherapy (arm B v arm A) and primary chemotherapy versus adjuvant chemotherapy (arm B v arm C).

RESULTS: Doxorubicin plus paclitaxel followed by CMF was well-tolerated as adjuvant or as primary chemotherapy. The addition of paclitaxel to adjuvant doxorubicin followed by CMF significantly improved RFS compared with adjuvant doxorubicin alone followed by CMF (hazard ratio [HR], 0.73; P = .03). Distant RFS was similarly improved (HR, 0.70; P = .027). There was no significant difference in RFS when the paclitaxel/doxorubicin/CMF chemotherapy was given before surgery compared with the same regimen given after surgery (HR, 1.21; P = .18). However, the rate of breast-conserving surgery was significantly higher with preoperative chemotherapy (63% v 34%; P < .001).

CONCLUSION: Incorporating paclitaxel into anthracycline-based adjuvant therapy resulted in a significant improvement in RFS and distant RFS. When given as primary systemic therapy, the paclitaxel-containing regimen allowed breast-sparing surgery in a significant percentage of patients.