A randomised study of tailored toxicity-based dosage of fluorouracil-epirubicin-cyclophosphamide chemotherapy for early breast cancer (SBG 2000-1)

Abstract

Study aim: Retrospective studies have demonstrated a worse outcome in breast cancer patients not developing leukopenia during adjuvant chemotherapy. The SBG 2000-1 is the first randomised trial designed to compare individually dosed chemotherapy without G-CSF support based on grade of toxicity to standard-dosed chemotherapy based on body surface area (BSA).

Methods: Patients with early breast cancer were included and received the first cycle of standard FEC (fluorouracil 600 mg/m², epirubicin 60 mg/m², cyclophosphamide 600 mg/m²). Patients with nadir leukopenia grade 0-2 after first cycle were randomised between either 6 additional courses of tailored FEC with increased doses (E 75-90 mg/m², C 900-1200 mg/m²) or fixed treatment with 6 standard FEC. Patients with grade 3-4 leukopenia were registered and treated with 6 standard FEC. Primary end-point was distant disease-free survival (DDFS).

Results: The study enrolled 1535 patients, of which 1052 patients were randomised to tailored FEC (N = 524) or standard FEC (N = 528), whereas 401 patients with leukopenia grade 3-4 continued standard FEC and formed the registered cohort. Dose escalation did not statistically significantly improve 10-year DDFS (79% and 77%, HR 0.87, CI 0.67-1.14, P = 0.32) or OS (82% and 78%, respectively, HR 0.89, CI 0.57-1.16, P = 0.38). Corresponding estimates for the registered group of patients were DDFS 79% and OS 82%, respectively.

Conclusions: The SBG 2000-1 study failed to show a statistically significant improvement of escalated and tailored-dosed chemotherapy compared with standard BSA-based chemotherapy in patients with low haematological toxicity, although all efficacy parameters showed a numerical advantage for tailored treatment.

Keywords: Adjuvant; Breast cancer; Chemotherapy; Dosage; Dose tailoring; Leukopenia.