The type of hormone therapy you receive will depend on whether you have been through the menopause


Tamoxifen works by preventing oestrogen from signalling to cancer cells, stopping them from growing. You will be offered tamoxifen if you haven’t been through the menopause and your breast cancer is hormone positive. Sometimes you might be given tamoxifen after the menopause if other treatments are not suitable for you.

To fully benefit from tamoxifen, you will need to take it for five to 10 years. This usually involves taking one tablet a day.

Aromatase inhibitors

Aromatase inhibitors work by reducing the production of oestrogen in the body and include the drugs anastrazole (Arimidex), exemestane (Aromasin) and letrozole (Femara). Aromatase inhibitors will only work if you have been through the menopause and your breast cancer is hormone positive.

Aromatase inhibitors are usually taken as tablets once a day in one of the following schedules:

  • If you have already been through the menopause when you are diagnosed, you should be offered five to 10 years of treatment with an aromatase inhibitor
  • If you are treated with tamoxifen initially and go through the menopause during this time, you may be switched to treatment with an aromatase inhibitor for a total of five to 10 years of hormone therapy

The exact treatment will vary from person to person. Your breast care team will discuss with you which programme of hormone therapy is likely to be most suitable for you.

Ovarian suppression

Ovarian suppression works by completely blocking the production of oestrogen by your ovaries. Whether ovarian suppression is right for you will depend on your breast cancer. It will only be suitable for you if your breast cancer is hormone positive and you have not been through the menopause, and will normally only be offered if you have also been treated with chemotherapy.

Ovarian suppression is normally given alongside tamoxifen. Sometimes though, you may be given ovarian suppression so that you can take an aromatase inhibitor even if you have not been through the menopause.

The most common method of ovarian suppression is treatment with a drug called goserelin (Zoladex) which is injected under your skin once a month. This can stop your ovaries producing hormones for up to five years.

Your ovaries can also be permanently removed by surgery, known as ovarian ablation. Radiotherapy can also be used to permanently stop your ovaries from working, but this is rare.

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Breast Cancer Now’s health information is produced following best practice guidelines developed by the Patient Information Forum. 

Find out more about how we develop our health information and the Patient Information Forum.