Purpose: The French Adjuvant Study Group 05 (FASG-05) showed that fluorouracil 500 mg/m2, cyclophosphamide 500 mg/m2, and epirubicin 100 mg/m2 (FEC 100) was superior to the same regimen with epirubicin 50 mg/m2 (FEC 50) in terms of disease-free survival (DFS) and overall survival (OS) in adjuvant treatment of early breast cancer. We report 10-year data on efficacy, and long-term side effects for FASG-05.
Patients and methods: We randomly assigned 565 patients to treatment with FEC 50 or FEC 100 after surgery. Postmenopausal patients also received tamoxifen for 3 years, and almost all patients (96%) also received radiotherapy.
Results: Median follow-up was 110 months. The 10-year DFS was 45.3% (95% CI, 41.9% to 48.7%) with FEC 50 and 50.7% (95% CI, 47.3% to 54.1%) with FEC 100 (Wilcoxon P = .036; log-rank P = .08). The 10-year OS was 50.0% (95% CI, 46.7% to 53.3%) with FEC 50 and 54.8% (95% CI, 51.3% to 58.3%) with FEC 100 (Wilcoxon P = .038; log-rank P = .05). Delayed cardiac toxicity (before relapse) occurred in four patients (1.5%) in the FEC 50 arm and three patients (1.1%) in the FEC 100 arm. Cardiac toxicity after relapse occurred in six (4.3%) and five (4.1%) patients treated with FEC 50 and FEC 100, respectively.
Conclusion: Treatment with adjuvant FEC 100 demonstrated superior DFS and OS versus FEC 50 at 10 years of follow-up. This survival advantage was not offset by long-term complications such as cardiac toxicity and second malignancy. Given the risk-benefit ratio, FEC 100 is a more optimal regimen for long-term survival in patients with poor prognosis.