Why is tamoxifen used in hormone therapy for cancer?

Some cancer cells carry hormone receptors. Oestrogen can attach to these receptors and send growth signals. Tamoxifen attaches to oestrogen receptors in breast tissue and reduces the effect of that signal. Its action can differ in other tissues, which is one reason its benefits and side effects need individual discussion.

It may be prescribed after initial treatment to lower the chance of cancer returning, or in other treatment settings chosen by the oncology team. It only helps when the cancer biology makes hormone blocking relevant; it is not a treatment for every cancer.

Take it exactly as prescribed and try to take it at a consistent time. Tell your team about every medicine, supplement and herbal product, because some can alter its effect. Do not stop it because of a side effect without discussing an alternative or adjustment.

Possible effects include hot flushes, sweating, mood changes, vaginal symptoms, nausea or changes in periods. Keep scheduled reviews so your team can discuss symptoms and monitor your treatment. If you have a uterus, ask what bleeding changes need assessment.

Contact your team promptly for unexpected vaginal bleeding, a new breast change, persistent leg swelling or pain, or troublesome vision changes. Seek urgent help for sudden chest pain, difficulty breathing, coughing blood, or sudden weakness or speech difficulty. Report pregnancy or a possible pregnancy promptly, because treatment planning may need to change.

Ask whether your tumour has hormone receptors, what benefit tamoxifen is intended to provide, how long treatment is planned, which symptoms should be reported, and whether contraception or pregnancy planning affects your care. Ask which medicines and supplements should be avoided.