BACKGROUND: To confirm the hypothesis that reducing the interval between surgery and adjuvant chemotherapy could improve prognosis, a randomized multicentric study of adjuvant perioperative chemotherapy (POC) in breast cancer was initiated. METHODS: A total of 552 patients were randomized to evaluate whether the addition of POC to standard adjuvant treatment significantly improved outcome. Patients were stratified according to menopausal status, with 362 patients in the postmenopausal group and 192 patients in the premenopausal group. Premenopausal women with positive axillary nodes, negative hormonal receptors, or grade 3 tumors received adjuvant mitoxantrone-based chemotherapy. Node-negative premenopausal patients with grade 1 or 2 tumors expressing hormonal receptors received no standard adjuvant treatment. All postmenopausal women received hormonal therapy (tamoxifen 20 mg/day for 3 years). The perioperative regimen was a 14 mg/m(2) mitoxantrone infusion at the end of tumor excision. RESULTS: With a median follow-up of 6.1 years, this study showed no significant advantage of POC on overall survival, disease-free survival, or metastasis-free survival for the total cohort or for the premenopausal and postmenopausal groups. CONCLUSIONS: POC was a safe procedure in this study. However, the addition of POC to standard adjuvant treatment offered no benefit in breast cancer adjuvant treatment.