Single-agent estramustine phosphate (EMP) is active in advanced breast cancer after failure with anthracyclines and...

Estramustine phosphate (EMP) is an oral cytotoxic agent that depolymerizes tubuline, a mechanism of action that has been revisited during the last decade. Because of its lack of haematological toxicity and favourable tolerance profile, EMP is a good candidate for palliative chemotherapy. The aim of the study was to assess its tolerance and efficacy in advanced breast cancer after failure with usual regimens.

Patients with a life expectancy of at least 12 weeks and bi-dimensionally measurable disease having received at least 1 line of chemotherapy (including taxanes and/or anthracyclines) for advanced breast cancer (ABC) were eligible. EMP was given daily at a dose of 10 mg/kg until disease progression, unacceptable toxicity or patient refusal to continue chemotherapy.

Forty patients were included between June 1998 and December 1999. Patients had previously received one to eight chemotherapy regimens (median is two) for ABC. Twenty-two patients (55%) had visceral involvement and eighteen patients (45%) had osseous, chest wall or soft tissue metastases. Adverse events leading to early interruption of EMP were grade 2 allergy (n = 1), grade 2-3 nausea (n = 6), deep-vein thrombosis (n = 1), grade 3 sepsis (n = 1). One patient died at twenty-four weeks from pulmonary embolism, and another at fourteen weeks from unknown cause. Seven objective responses were observed (17.5%; 95% confidence interval (CI): 6%-30%). Median time to failure was 24 weeks (14-52+) in responding patients. All objective responses but one were observed in patients with visceral metastases. In 10 other patients (25%), disease remained stable with a median time to failure of 27 weeks (16-50); 6 of these experienced a decrease of consumption of analgesics or an improvement of performance status.

EMP is an active drug in ABC after failure with taxanes and anthracyclines, whose tolerance profile appears favourable.