Hormones can stimulate some breast cancer cells to grow. Hormone therapy works by either lowering the amount of hormones in the body or by blocking them from getting to breast cancer cells. Hormone therapy is also known as endocrine therapy.
There are a number of different types of hormone therapy. The type you need depends on a number of factors. One of the most common types of hormone therapy used for breast cancer is tamoxifen.
What are hormones?
Hormones are made naturally in the body. They control the growth and activity of normal cells.
These hormones can stimulate the growth of some breast cancer cells.
How does hormone therapy work?
Hormone therapy can lower the levels of oestrogen or progesterone in the body, or block their effects.
Hormone therapy is only likely to work if the breast cancer cells have oestrogen receptors (ER). Your doctor checks your cancer cells for these receptors when you are diagnosed.
Most breast cancers have oestrogen receptors. They are called oestrogen receptor positive or ER positive (ER+) breast cancer. Around 80 out of every 100 breast cancers (around 80%) are oestrogen receptor positive.
When you might have hormone therapy
You usually have hormone therapy after surgery. Some people may also have it before surgery.
It is also a possible treatment for breast cancer that has spread to other parts of the body. This is secondary breast cancer.
Hormone therapy after surgery
The most common way to have hormone therapy for breast cancer is after surgery. This is called adjuvant treatment. The aim of hormone treatment after surgery is to lower the risk of the cancer coming back.
If you are also having chemotherapy after surgery, you start hormone therapy once the chemotherapy finishes. If you are having radiotherapy after surgery, you can usually have hormone therapy at the same time. Or you may start hormone therapy after your radiotherapy.
You usually have hormone therapy for 5 years or more. But exactly how long you have it depends on:
- the type of drug you have
- any side effects you might have
- your individual situation such as whether you have had the menopause
Hormone therapy before surgery
Treatment before surgery is called neo adjuvant therapy. You may have it to try to shrink a large cancer. This might mean that you can have a smaller operation. For example, you might be able to have just the tumour removed (a lumpectomy) instead of the whole breast (mastectomy).
You have check ups with your doctor during neo adjuvant hormone therapy to see if your cancer is getting smaller.
If you can’t have surgery
Surgery is the main treatment for breast cancer, but some women have health problems that mean they can’t have surgery. Some women choose not to have surgery.
In this case, if your breast cancer is oestrogen receptor positive, your doctor might recommend hormone therapy. This treatment won't get rid of the cancer but can stop it growing or shrink it.
The treatment can often control the cancer for some time. Your doctor might change you to a different type of hormone treatment if your cancer starts growing again.
Hormone therapy for secondary breast cancer
Breast cancer can spread from where it started to other parts of the body. This is secondary or advanced breast cancer.
The aim of treatment for secondary breast cancer is to control the cancer and give you a good
You might have hormone therapy when secondary breast cancer is first diagnosed. Or after you have had treatment with chemotherapy.
Types of hormone therapy
The type of hormone treatment you have depends on different factors, including:
- whether or not you have had the menopause
- the risk of your cancer coming back
- the side effects of the drug
There are different types of hormone therapy. These include:
Tamoxifen is one of the most commonly used hormone therapies for breast cancer. Women who are still having periods (are pre menopausal) and women who have had their menopause (post menopausal) can take tamoxifen. You might also have this treatment if you are a man with breast cancer.
Tamoxifen works by blocking the oestrogen receptors. It stops oestrogen from telling the cancer cells to grow.
Your doctor might recommend you take tamoxifen to lower the risk of breast cancer coming back (recurring) after surgery. You may also have tamoxifen before surgery or if you have secondary breast cancer.
You usually take tamoxifen for 5 years. Your doctor might recommend that you take it for another 5 years after this if there is a high risk of your cancer coming back. They will weigh up the benefit of taking the drug for longer with other factors, such as any side effects you have and whether you want to have children.
If you can't have tamoxifen for any reason, your doctor might recommend you have other types of hormone therapy such as an aromatase inhibitor. Or your doctor might recommend surgery to remove your ovaries.
If you have your menopause while on tamoxifen, your doctor might suggest you switch to an aromatase inhibitor such as letrozole.
Aromatase inhibitors (AIs)
You might have an aromatase inhibitor if you have had the menopause.
After menopause, your ovaries stop producing oestrogen. But your body still makes small amounts by changing other hormones (called androgens) into oestrogen. Aromatase is the enzyme that makes this change happen. Aromatase inhibitors block the enzyme aromatase so that it can’t change androgens into oestrogen.
Examples of aromatase inhibitors used to treat breast cancer include:
- anastrozole (Arimidex)
- letrozole (Femara)
- exemestane (Aromasin)
You are most likely to have anastrozole or letrozole for 5 years. Or you might have one of these drugs for 2 years followed by tamoxifen for 3 years.
If you can't have an aromatase inhibitor, you have tamoxifen for 5 years.
Other options might include:
- taking tamoxifen for 2 to 3 years and then switching to an aromatase inhibitor for a total of 5 years
- taking tamoxifen for 5 years and then letrozole for a further 5 years
Your doctor will think about your general health and possible side effects of the drugs when deciding which hormone treatment will be best for you.
You might have aromatase inhibitors in combination with other drug treatments such as:
Luteinising hormone releasing hormone (LHRH) agonists or LH blockers
In pre menopausal women, doctors might use a type of hormone treatment to stop the ovaries from producing oestrogen. These are called luteinising hormone releasing hormone (LHRH) agonists. For example, goserelin (Zoladex) and leuprorelin (Prostap, Lutrate). You might have this on its own or with other hormone therapy drugs such as tamoxifen or exemestane.
LHRH drugs work by blocking a hormone made in the
When you stop having the drug, your ovaries should start working again. But, if you're close to the age at which your menopause would naturally start, your periods might not return.
Fulvestrant is a type of hormone therapy for post menopausal women with secondary breast cancer that is
Fulvestrant works in two ways. Firstly, it blocks oestrogen receptors, in a similar way to tamoxifen. But it can also change the shape of oestrogen receptors in the cancer cells, so the oestrogen can’t attach to them.
You might have fulvestrant in combination with other drug treatments such as:
Surgery to stop the ovaries from working
You might choose to have an operation to remove your ovaries instead of having drug treatment to stop them from working. This type of treatment is also called ovarian ablation.
The type of surgery you have is called laparoscopic oophorectomy. You have it under
The surgeon makes a number of small cuts into your tummy (abdomen). They put a long bendy tube called a laparoscope into one of the cuts. The laparoscope connects to a video screen.
The surgeon puts small instruments through the other cuts to carry out the operation and remove the ovaries. They close the cuts with stitches and cover them with small dressings.
Removing your ovaries causes you to have a sudden menopause. The symptoms include hot flushes, sweating and mood swings.
Finding out more about hormone therapy drugs
Check what is the name of the hormone therapy with your doctor or nurse, then take a look at our A to Z list of cancer drugs.
How you have hormone therapy
How you have treatment depends on the type of hormone therapy you have.
Tamoxifen and aromatase inhibitors
You take these as a tablet once a day. Try to take it at the same time each day, preferably after a meal. Swallow the tablets whole with a drink of water.
Tamoxifen is also available as a liquid.
You must take tablets according to the instructions your doctor or pharmacist gives you.
Speak to your pharmacist if you have problems swallowing the tablets.
Whether you have a full or an empty stomach can affect how much of a drug gets into your bloodstream.
You should take the right dose, no more or less.
Talk to your healthcare team before you stop taking a cancer drug or if you miss a dose.
Luteinising hormone releasing hormone (LHRH) agonists
You usually have these as an injection just under the skin in your tummy (abdomen). It is called a depot injection, which means that the drug is slowly absorbed into your body over a period of time. You may also have leuprorelin as an injection into a muscle in your leg or buttocks.
You can have the injections every 4 weeks or 12 weeks.
You usually have fulvestrant as an injection into a muscle once a month. You may have some soreness and swelling around the injection site for a day or 2 afterwards.
Some side effects are common to all hormone therapies. Some effects vary from drug to drug.
The main side effects of hormone therapy include:
- hot flushes and sweating
- changes to your periods if you are pre menopausal
- less interest in sex
- vaginal dryness or discharge
- feeling sick
- painful joints
- mood changes
Many women find that the side effects are often worse at the start of treatment. They usually settle down after a few weeks or months.
Tell your doctor or nurse if you have any side effects. They may be able to help reduce them.
A side effect of aromatase inhibitors and goserelin is bone thinning (osteoporosis) or weakening. This can sometimes cause breaks (fractures) in the bones. If you are starting treatment with an aromatase inhibitor you might have a
Weight bearing exercise such as walking can help to build up the bones and protect them. Check with your doctor before starting any new type of exercise, especially if you have not exercised for a while.
You might also have calcium and vitamin D supplements to help reduce the effect on your bones.
All the treatments that stop your ovaries working give you an early menopause, but this might be temporary with goserelin. Some women find this very difficult to deal with. You are likely to have menopausal symptoms that start very suddenly.