Some cancers need female hormones (oestrogen) to grow and reproduce. In these cases hormone therapy may be given to deprive the cancer cells of the hormones they need to grow.
How does it work?
Hormone therapy is designed to either lower the level of oestrogen in your body or to stop the oestrogen from stimulating the cancer cells. Your doctor will probably recommend this treatment if your tumour is oestrogen or progesterone receptor positive.
There are different hormone therapies for women who are pre-menopausal and those who are post-menopausal due to the different levels of oestrogen produced throughout these stages.
Some of the different hormone therapies available include:
- Anti-oestrogens - stop oestrogen in the body from attaching to cancer cells. One of the most well known is tamoxifen. Tamoxifen can be used in women who are pre-menopausal and women who are post-menopausal.
- Aromatase Inhibitors (AIs) - block oestrogen production, but only work for post-menopausal women. AIs commonly used in Australia include Arimidex, Femara and Aromasin. There are also generic versions of these drugs available.
- Ovarian suppression - stops the ovaries producing oestrogen. This is often recommended for women who haven't been through menopause. It may involve removing the ovaries surgically, a short course of radiotherapy or a monthly injection.
- Progestogens - used if the secondary breast cancer cells are not controlled by anti-oestrogen treatments or aromatase inhibitors.
Side effects of hormone therapy
- Some of the aromatase inhibitors (e.g. Arimidex) can cause joint pain and stiffness.
- The AIs can also lead to bone loss. If you are being treated with an AI you may be referred for bone mineral density tests to monitor your bone mineral density levels, particularly if you are at risk of developing osteoporosis. Bone mineral density tests are usually done using DXA X-ray. A bone mineral density test is different from the bone scan that you may have to check whether your cancer has spread to other parts of your body. You may also have your Vitamin D levels checked. For more information about bone health and Vitamin D, read our Bone health page.
- Anti-oestrogens and aromatase inhibitors may cause hot flushes and vaginal dryness.
- Progestogens may cause nausea and can also increase appetite, which can lead to weight gain.
Note: Hormone therapy is sometimes confused with hormone replacement therapy (HRT), but they are completely different.
- BCNA's Hormone therapy and breast cancer booklet has information on managing the side effects of hormone therapies, including hot flushes, vaginal symptoms, thinning hair and nails, and joint pain.
- The page on managing symptoms and side effects may also be helpful.