Epirubicin and docetaxel as first-line treatment for hormonal receptor positive metastatic breast cancer: the predictive value of luminal subtype: A retrospective cohort analysis

Background: We retrospectively evaluated the efficacy of first-line epirubicin and docetaxel in patients with metastatic, hormonal receptor (HR)-positive, and human epidermal growth factor receptor-2-negative breast cancer. A subgroup analysis evaluated the predictive value of immunohistochemistry-defined luminal subtype. Methods: We included patients with at least one visceral and measurable site of metastatic disease. Patients were grouped as luminal A (HR+ and Ki67<13%) or luminal B (HR+ and Ki67>13%). Results: Forty-four patients were entered and prognostic variables were similar between the subgroups. Luminal B patients achieved higher objective response rate than luminal A (69% versus 19%; P=0.001), longer time to progression (12.2 months versus 8.6 months; P=0.039), and longer overall survival (24.6 months versus 19.5 months; P=0.041). The multivariate analysis confirmed the predictive value of luminal B subtype for longer time to progression. Conclusions: Identification by Ki67 labelling index of human epidermal growth factor receptor-2-negative luminal A could predict a substantial benefit from systemic chemotherapy. Endocrine therapy would be the most appropriate therapy for luminal A tumours.