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Hormone therapy

Hormone therapies are drugs used to treat hormone receptor positive breast cancer.

Around two-thirds of breast cancers are hormone receptor positive, which means that they need female hormones (oestrogen and/or progesterone) to grow and reproduce. Most women with hormone receptor positive breast cancer will be offered hormone therapy.

Hormone therapy is given as an oral medication. It is usually taken daily for at least five years after the completion of your other breast cancer treatments (surgery, chemotherapy and/or radiotherapy).

Tamoxifen is one of the best known hormone therapy medications. It can be used to treat pre and post-menopausal women. Arimidex, Aromasin and Femara (and new generic brands of these drugs) are also hormone therapies, however they are only suitable for women who have completed menopause.

Hormone therapy is sometimes confused with hormone replacement therapy (HRT), but they are completely different.

How does hormone therapy work?

Hormone therapy works by stopping oestrogen from ‘feeding’ the breast cancer cells. It has been found to be very effective in reducing the risk of the cancer spreading to other parts of the body, or of a new breast cancer developing in the same or other breast.

Recent research has shown that, for some women, taking tamoxifen for 10 years is better than five. Your medical oncologist will be able to talk to you about whether continuing tamoxifen beyond five years could be of benefit to you.

Side effects

Hormone therapy can have side effects, including:

  • Menopausal symptoms such as hot flushes, night sweats, heart palpitations
  • Anxiety
  • Sleep disturbance
  • Fatigue

The aromatase inhibitors can also cause pain, joint stiffness and vaginal dryness.

Generally, these side effects can be managed. BCNA’s booklet Hormone therapy and breast cancer includes suggestions for managing side effects of hormone therapy treatment.

BCNA’s Breast cancer and sexual wellbeing booklet has helpful advice on managing the impact of hormone therapy treatments on sexual wellbeing.

If you are finding side effects difficult to manage, talk to your medical oncologist. She or he may be able to switch you to one of the other hormone therapy drugs.

Some hormone therapy treatments can cause bone density loss. This can result in bone fractures and osteoporosis. Your doctor may recommend that you have a bone mineral density scan, called a DXA or DEXA scan, before starting your treatment. You may also have your calcium and Vitamin D levels checked. More information is available on the Bone health page of this website.

More information

  • Find more information on our My Journey online tool which is a free resource that provides up-to-date, reliable information tailored to your changing needs and circumstances at all stages of your breast cancer journey.
  • Join our online network if you think that talking to others online and sharing experiences will help.
  • Westmead Breast Cancer Institute’s Hormone (Endocrine) treatment for early breast cancer fact sheet can be viewed here
  • Read more about hormone therapies on Cancer Australia's website