Fluorouracil and dose-dense chemotherapy in adjuvant treatment of patients with early-stage breast cancer: an open-label, 2 × 2 factorial, randomised phase 3 trial

Background: Whether addition of fluorouracil to epirubicin, cyclophosphamide, and paclitaxel (EC-P) is favourable in adjuvant treatment of patients with node-positive breast cancer is controversial, as is the benefit of increased density of dosing. We aimed to address these questions in terms of improvements in disease-free survival.

Methods: In this 2 × 2 factorial, open-label, phase 3 trial, we enrolled patients aged 18-70 years with operable, node positive, early-stage breast cancer from 81 Italian centres. Eligible patients were randomly allocated in a 1:1:1:1 ratio with a centralised, interactive online system to receive either dose-dense chemotherapy (administered intravenously every 2 weeks with pegfilgrastim support) with fluorouracil plus EC-P (FEC-P) or EC-P or to receive standard-interval chemotherapy (administered intravenously every 3 weeks) with FEC-P or EC-P. The primary study endpoint was disease-free survival, assessed with the Kaplan-Meier method in the intention-to-treat population. Our primary comparisons were between dose schedule (every 2 weeks vs every 3 weeks) and dose type (FEC-P vs EC-P). This study is registered with ClinicalTrials.gov, number NCT00433420.

Findings: Between April 24, 2003, and July 3, 2006, we recruited 2091 patients. 88 patients were enrolled in centres that only provided standard-intensity dosing. After a median follow-up of 7·0 years (interquartile range [IQR] 4·5-6·3), 140 (26%) of 545 patients given EC-P every 3 weeks, 157 (29%) of 544 patients given FEC-P every 3 weeks, 111 (22%) of 502 patients given EC-P every 2 weeks, and 113 (23%) of 500 patients given FEC-P every 2 weeks had a disease-free survival event. For the dose-density comparison, disease-free survival at 5 years was 81% (95% CI 79-84) in patients treated every 2 weeks and 76% (74-79) in patients treated every 3 weeks (HR 0·77, 95% CI 0·65-0·92; p=0·004); overall survival rates at 5 years were 94% (93-96) and 89% (87-91; HR 0·65, 0·51-0·84; p=0·001) and for the chemotherapy-type comparison, disease-free survival at 5 years was 78% (75-81) in the FEC-P groups and 79% (76-82) in the EC-P groups (HR 1·06, 0·89-1·25; p=0·561); overall survival rates at 5 years were 91% (89-93) and 92% (90-94; 1·16, 0·91-1·46; p=0·234). Compared with 3 week dosing, chemotherapy every 2 weeks was associated with increased rate of grade 3-4 of anaemia (14 [1·4%] of 988 patients vs two [0·2%] of 984 patients; p=0·002); transaminitis (19 [1·9%] vs four [0·4%]; p=0·001), and myalgias (31 [3·1%] vs 16 [1·6%]; p=0·019), and decreased rates of grade 3-4 neutropenia (147 [14·9%] vs 433 [44·0%]; p<0·0001). Addition of fluorouracil led to increased rates of grade 3-4 neutropenia (354 [34·5%] of 1025 patients on FEC-P vs 250 [24·2%] of 1032 patients on EC-P; p<0·0001), fever (nine [0·9%] vs two [0·2%]), nausea (47 [4·6%] vs 28 [2·7%]), and vomiting (32 [3·1%] vs 15 [1·4%]).

Interpretation: In patients with node-positive early breast cancer, dose-dense adjuvant chemotherapy improved disease-free survival compared with standard interval chemotherapy. Addition of fluorouracil to a sequential EC-P regimen was not associated with an improved disease-free survival outcome.

Funding: Bristol-Myers Squibb, Pharmacia, and Dompè Biotec.