Estramustine phosphate

How it works

It acts as a microtubule-disrupting agent by binding microtubule-associated proteins and also exerts an oestrogenic effect that suppresses testosterone, inhibiting tumour cell growth.

Prescribing in practice

• Its oestrogenic activity markedly increases the risk of venous thromboembolism and cardiovascular events, so it is contraindicated in active thromboembolic and significant cardiac disease.
• Use only under specialist oncology supervision, with caution in hepatic impairment and a history of thrombosis.
• Absorption is reduced by milk, dairy products and calcium-containing preparations, which should be separated from dosing.

Monitoring

Monitor liver function, blood pressure and for signs of thromboembolic or cardiovascular complications.

Counselling the patient

• Avoid taking with milk, dairy or calcium products as these reduce absorption.
• Seek urgent help for chest pain, breathlessness, or a painful, swollen leg.
• Gynaecomastia and fluid retention can occur because of the oestrogen component.

Evidence & guidelines

Use of estramustine in advanced prostate cancer is based on long-standing clinical experience and the summary of product characteristics rather than current first-line recommendations.