Some breast cancers have receptors for the female hormones, oestrogen or progesterone. They can have receptors for just one hormone or both of them. Hormones attach to the receptors and make the cancer grow.

These cancers are called hormone-sensitive breast cancers.

Hormonal therapy is a way of treating hormone-sensitive cancers. They either:

• stop the body from making the hormone, or
• stop the hormone from affecting the cancer cells.

Hormonal therapy for breast cancer works by:

• blocking the effect of oestrogen on the cancer cells, e.g.Tamoxifen
• reducing the amount of oestrogen produced by the ovaries, e.g. surgical removal or drug treatment
• reducing the amount of oestrogen produced by other parts of the body (not the ovaries), e.g. aromatase inhibitors, like anastrazole (Arimadex), exemestane (Aromasin) and letrozole (Femara).

Hormonal therapy for breast cancer is given for different reasons. They can be used:

• in hormone-sensitive early breast cancer to reduce the chance of the cancer coming back
• in hormone-sensitive advanced cancer to slow the growth or spread of the cancer.