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No added benefit for doxorubicin + docetaxel vs doxorubicin + cyclophosphamide

SABCS 2019

In one of the first studies to evaluate taxanes versus anthracyclines in the neoadjuvant setting, no added clinical benefit in either overall survival (OS) or disease-free survival (DFS) for the simultaneous administration of doxorubicin and docetaxel compared to doxorubicin and cyclophosphamide was observed during a median of 119 months of follow-up. Importantly, this does not exclude the possibility of the occurrence of a smaller benefit than the study was powered to detect, according to researchers.

In this phase 3, multicentre, randomised trial involving 25 centres in the United Kingdom, Ireland, and Belgium, the long-term outcome of women with primary or locally advanced breast cancer who were randomised to receive either doxorubicin and cyclophosphamide (n=181) or doxorubicin and docetaxel (n=182) as primary chemotherapy were compared [1]. The maximum number of cycles was 6 cycles of either doxorubicin (60 mg/m2) + cyclophosphamide (600 mg/m2) administered intravenously every 3 weeks or doxorubicin (60 mg/m2) + docetaxel (75 mg/m2) intravenously every 3 weeks, followed by surgery on completion of chemotherapy. Eligible patients had histology-proven breast cancer with primary tumours ≥3 cm, inflammatory or locally advanced disease, and no evidence of distant metastases, ECOG performance status 0-1, as well as adequate haematologic, renal, and liver function. Patients were evaluated every 3 weeks and tumour response was determined by clinical assessments of bi-dimensionally measurable disease using standard response criteria. The primary endpoint of this study was the overall clinical response rates to primary chemotherapy.

It was shown that the pathologic complete response rate in the breast was 24% for doxorubicin + cyclophosphamide and 21% for doxorubicin + docetaxel, respectively (P=0.61). At a median follow-up of 119 months, no significant difference between treatment groups for OS (P=0.274) and DFS (P=0.327) was detected. The 10-year OS for doxorubicin + cyclophosphamide was 54% (95% CI 47-62%); this was 60% (95% CI 52-67%) for doxorubicin + docetaxel. The 10-year DFS was 49% (95% CI 42-57%) for doxorubicin + cyclophosphamide and 51% (95% CI 43-58%) for doxorubicin + docetaxel.

Metastatic breast cancer accounted for 89% of deaths in patients who were treated with doxorubicin + cyclophosphamide and 86% in those treated with doxorubicin + docetaxel. Oestrogen receptor (ER) and nodal status were independent prognostic factors for DFS and OS (P<0.0005).

1. Stavraka C, et al. P2-16-15. SABCS 2019.

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