Hormonal therapy (also called anti-hormone treatment) is used to treat breast cancers that are hormone receptor positive. These cancers have receptors for the hormones oestrogen and/or progesterone; they are called ER and/or PR positive cancer. Around 70% of breast cancers are ER positive.
Hormonal therapy may be recommended after other treatments for breast cancer like surgery, chemotherapy or radiotherapy. Sometimes it is used to shrink breast cancer before other treatment is given. The aim of hormonal therapy is to ‘starve’ breast cancer cells of the hormone (oestrogen) that makes them grow. This lowers the risk of breast cancer coming back or a new breast cancer developing in the treated breast or in the other breast.
There are several different types of hormonal therapies. Some are taken as tablets (tamoxifen or aromatase inhibitors) and others may involve surgery, injections or radiotherapy to turn off ovaries in premenopausal women.
This page explains the following types of hormonal therapies to turn off ovaries in premenopausal women:
Hormonal therapies can also be used to treat ductal carcinoma in situ (DCIS) and to reduce the risk of breast cancer in women with a strong family history or other risk factors for breast cancer.
Breast cancers that are hormone receptor positive have receptors for the female hormones oestrogen and/or progesterone on the inside of the cancer cells.
In breast cancer cells that are hormone receptor positive, oestrogen and/or progesterone, which are naturally produced in the body, make the cancer grow. You can think of it as the receptor being the lock and oestrogen being the key. The oestrogen fits into the receptor and switches the cancer cell on, causing it to grow. Hormone therapy for breast cancer can ‘starve’ cancer cells by upsetting this process.
Testing for hormone receptors is part of the routine pathology testing following surgery. Testing is done on a core biopsy sample if surgery is not planned. Your doctor will be able to tell you if your breast cancer is hormone receptor positive or not. Most breast cancer (around 70%) is hormone receptor positive.
The hormonal therapies described on this page only work against breast cancers that are hormone receptor positive. Other treatments need to be used for cancers that are hormone receptor negative.
Tamoxifen has been used for many years to treat breast cancer. It has been proven to be a very effective treatment. Tamoxifen can substantially reduce the chance of breast cancer coming back and of new breast cancers developing.
Tamoxifen works by blocking the oestrogen receptor inside the breast cancer cell. This stops oestrogen making the breast cancer cell grow.
Tamoxifen is taken as a tablet once a day. It may be prescribed as a 5 year course after other treatments for early breast cancer like surgery, chemotherapy and radiotherapy have been completed. In some cases tamoxifen is prescribed for two or three years before switching to a different hormonal therapy like an aromatase inhibitor (see next section). Sometimes tamoxifen is recommended for up to ten years. If tamoxifen is being used to treat metastatic breast cancer (breast cancer that has spread beyond the breast), it is used for as long as it keeps working.
Tamoxifen is a very effective hormonal therapy for women before or after menopause.
Tamoxifen:
Most women do not experience significant side effects while taking tamoxifen.
Tamoxifen does not cause menopause, but its side effects are like those that many women experience after menopause
Common side effects:
Uncommon side effects:
Rare side effects:
Very rare side effects:
If you are worried about side effects, talk to your doctor
You should not become pregnant or breast feed while taking tamoxifen or for 1 to 2 months after stopping tamoxifen.
Tamoxifen can increase fertility so you must use contraception while you are taking tamoxifen if you have not been through menopause. Use a barrier method such as condoms, a diaphragm or a non-hormonal intra-uterine device (IUD). You must not take the oral contraceptive pill with tamoxifen.
Tamoxifen can interact with Warfarin (a drug used to thin the blood to prevent blood clotting). If you take Warfarin you should tell your doctor.
You should not take other hormone medications while you take tamoxifen. You can continue to take all other medications prescribed by your doctor.
Aromatase inhibitors are another hormone treatment for breast cancer. They are an alternative to tamoxifen. Aromatase inhibitors only work in post-menopausal women. Women who are post-menopausal, either naturally or as a result of treatment such as chemotherapy or surgical removal of the ovaries, may be prescribed aromatase inhibitors.
If you and your doctor don’t know whether or not you have gone through menopause, you may be prescribed tamoxifen for a year or more and then changed to an aromatase inhibitor once menopause is confirmed. If you have not been through menopause these drugs do not work effectively.
In women before menopause, most if not all oestrogen is made in the ovaries. After menopause, an enzyme called aromatase helps to make oestrogen in the peripheral body tissues such as muscle, fat and the adrenal glands. Aromatase inhibitors work by blocking this enzyme, thereby reducing the production of oestrogen to feed the breast cancer cells.
Aromatase inhibitors are taken as a tablet once a day. The treatment course is usually five years.
Like tamoxifen, aromatase inhibitors can be used before or after other treatments for breast cancer such as surgery, chemotherapy and radiotherapy.
Aromatase inhibitors can also be used after two to three years of tamoxifen to complete the course of hormonal treatment. Sometimes, a 10-year course of aromatase inhibitor is recommended. Aromatase inhibitors can also be used to treat breast cancer that has recurred or spread.
Three aromatase inhibitors are used in Australia:
Aromatase inhibitors:
Common side effects:
Uncommon side effects:
Aromatase inhibitors can reduce bone density. This may increase the risk of bone fracture.
To keep your bones healthy while you are taking this medication, your doctor may recommend that you:
If you do show signs of bone thinning (osteopenia) or weakening (osteoporosis) you may need to see your GP or specialist for special treatment for your bones.
‘Turning off’ or removing the ovaries lowers the levels of oestrogen in the blood. This is another way of ‘starving’ cancer cells of oestrogen to stop them growing. This treatment only works before menopause. This treatment is not necessary for women who have already gone through menopause because the ovaries naturally stop making oestrogen after menopause.
Turning off or removing the ovaries:
Surgical removal of the ovaries reduces the risk of breast cancer returning and has the added benefit of reducing the risk of developing cancer of the ovaries, although cancer of the ovaries is uncommon.
Turning off the ovaries with medication
The ovaries can be shut down temporarily with medication. This is usually done by giving monthly injections of goserelin (Zoladex®). This gradually causes the levels of oestrogen to fall, which leads to temporary menopause.
The menstrual periods stop and other symptoms of menopause may develop (see below). These symptoms can be reversed. If the injections are stopped, the oestrogen levels and menstrual periods return to normal.
Some women who are considering having their ovaries removed have these injections for a few months to ‘test out’ the menopausal symptoms. They still have the choice of reversing the effect if the side effects are too intense.
The operation to remove the ovaries is called oophorectomy. Surgical removal of the ovaries is a permanent way to reduce the levels of oestrogen. It is a very effective treatment to stop early breast cancer returning or to slow the progress of metastatic cancer. This can also reduce the risk of developing ovarian cancer.
Surgery to remove the ovaries can be done with keyhole surgery (using a laparoscope) or with an open operation (making an incision along the bikini line). Your surgeon will discuss with you the pros and cons of these different techniques. Oophorectomy is done under a general anaesthetic (while you are asleep). Usually the fallopian tubes are also removed but the uterus (womb) is left intact.
After oophorectomy, the symptoms of menopause may come on suddenly. This is different to turning off the ovaries with medication which brings menopausal symptoms on gradually.
If you do get troublesome side-effects on these treatments, we can often find a different drug or a different dose that will help, so it is important not to just stop the drug, but to talk to your specialist.
All of the hormonal therapies described in this brochure reduce the effects of oestrogen in your body.This means that they can all cause symptoms of menopause like hot flushes, mood swings, vaginal symptoms and a change in sex drive.
The range and severity of menopausal symptoms vary from one woman to another. Some women may experience very few menopausal symptoms. Symptoms will usually become less noticeable with time, as the body adjusts to lower oestrogen levels.
In general, hormone replacement therapy is not recommended in women who have had breast cancer but there are other things that can help. More information can be found on the Menopause after breast cancer page.
If you would like more information about hormone treatment ask your surgeon, cancer specialist (oncologist), breast care nurse or other health professional.
| Organisation | Contact |
|---|---|
| Westmead Breast Cancer Institute | (02) 8890 6728 |
| Cancer Council Helpline | 13 11 20 |
| Breast Cancer Network Australia | 1800 500 258 |
| Cancer Australia |
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