Individually tailored toxicity-based 5-fluorouracil, epirubicin and cyclophosphamide (FEC) therapy of metastatic breast cancer

Abstract

Chemotherapy dosing only based on body surface area (BSA) results in marked pharmacokinetic and toxicity variations, which may result in an inferior outcome for some patients. A toxicity-based dosing schedule for individually tailored treatment with granulocyte colony-stimulating factor (G-CSF) supported 5-fluorouracil (F), epirubicin (E) and cyclophosphamide (C) (dFEC) was developed and studied in patients with metastatic breast cancer with the purpose to determine its efficiency and toxicity. Twenty-six women, median age 48 years, were included and the individual E and C doses were tailored stepwise based on the recorded hematological toxicity. Twenty-one patients (81%; 95% confidence interval (CI), 66% to 96%) had an objective response, including six complete responses (23%; CI, 7%–39%). At median follow-up of 113 months, the median time to progression and median overall survival were 14 and 36 months, respectively. The delivered dose intensity was high but varied substantially between patients (ranges F 126–202, E 14.4–36.0, C 160–510 mg/m²/w). The dominating grade III/IV toxicity was nausea (12% of patients) and febrile neutropenia (31% of patients). The tailored and dose-escalated FEC was highly active and feasible in metastatic breast cancer and may provide a pragmatic way of overcoming the shortcomings of standard BSA-based dosing.