How does risk-reducing endocrine therapy work?

Some breast cells respond to oestrogen or related hormones. Medicines used for risk reduction can occupy hormone receptors or reduce the hormone signal reaching breast tissue. This is different from chemotherapy: the medicine is intended to reduce the chance of a hormone-sensitive cancer developing, rather than destroy an existing tumour. Suitability depends on your age, health, breast history, family history, inherited risk such as a BRCA gene mutation, and whether you have had lobular carcinoma in situ. The medicine chosen also affects which side effects and precautions apply. Risk reduction is not a promise that cancer cannot occur, so breast awareness and the screening plan advised for you still matter.

Take the prescribed medicine exactly as directed and tell your clinician about all medicines, supplements and previous blood clots or bleeding problems. Keep follow-up appointments so symptoms and ongoing suitability can be reviewed. Report troublesome hot flushes, mood changes, vaginal symptoms or menstrual changes rather than stopping on your own. Ask whether pregnancy must be avoided and which contraception is suitable. Do not share tablets or change the dose without medical advice.

Seek urgent medical help for sudden chest pain, difficulty breathing, coughing blood, or painful swelling in one leg, as these can signal a blood clot. Contact your care team promptly for unusual vaginal bleeding, severe headache, vision changes or a new breast change. These symptoms do not establish a diagnosis, but they need timely assessment.

Ask what risk factor makes this treatment relevant to you, which medicine is proposed, how long it is expected to continue, and what benefits and side effects are realistic. Clarify pregnancy planning, clot risk, interactions, screening and what to do after a missed dose.