Hormone therapy for breast cancer

What are hormones?

Hormones are natural substances made by glands in our bodies. The network of glands that make hormones is called the endocrine system. Hormones move around the body in our bloodstream. They act as messengers between one part of the body and another. They are responsible for many functions in our body, including the growth and activity of certain cells and organs.

Before the ​menopause, the ovaries produce the hormones oestrogen and progesterone. After the menopause oestrogen is made in body fat and muscle.

Oestrogen and progesterone can stimulate the growth of some breast cancer cells.

Find out more about the endocrine system

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. 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.

When might you 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 secondary breast cancer. This is breast cancer that has spread to other parts of the body.

Find out more about 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 having chemotherapy after surgery, you start hormone therapy once the chemotherapy finishes.

If you are having radiotherapy you usually have hormone therapy at the same time. Or you may start hormone therapy after your radiotherapy.

You usually have hormone therapy for 5 to 10 years. Exactly how long you have it depends on:

• the type of drug you have

• any side effects you might have

• the type and grade of your breast cancer

• 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 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 called secondary or advanced breast cancer.

The aim of treatment for secondary breast cancer is to control the cancer and give you a good ​quality of life.

You might have hormone therapy when secondary breast cancer is first diagnosed. Or after treatment with chemotherapy.

Find out about secondary breast cancer

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

Tamoxifen is one of the most commonly used hormone therapies for breast cancer. You might have it if:

• you are still having periods (pre or peri menopausal)

• your periods have stopped (post menopausal)

• 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 at least 5 years. Your doctor might recommend that you take it for longer. They will tell you how long you need to take it. They will weigh up the benefit of taking the drug for longer with other factors. This includes any side effects you have and whether you want to have children.

If you can't have tamoxifen your doctor might recommend you have other types of hormone therapy. Or they 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.

Read more information about tamoxifen and its possible side effects

Aromatase inhibitors (AIs)

You might have an aromatase inhibitor if you have been through 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 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 at least 5 years. Your doctor might recommend that you take it for longer. They will let you know how long you need to take it. They will think about your general health and possible side effects of the drugs when deciding which hormone treatment will be best for you.

If you have secondary breast cancer you might have aromatase inhibitors in combination with other drug treatments such as:

• palbociclib

• ribociclib

• abemaciclib

Luteinising hormone releasing hormone (LHRH) agonists or LH blockers

A gland in the brain called the pituitary gland produces luteinising hormone (LH). Luteinising hormone controls the amount of oestrogen and progesterone made by the ovaries.

LH blockers are also called luteinising hormone releasing hormone (LHRH) agonists. They stop the production of luteinising hormone. They do this by blocking the signal from the pituitary gland to the ovaries. So, the ovaries stop making oestrogen or progesterone.

You will only have this treatment if you have not had your menopause yet. After menopause, your ovaries don’t produce hormones, so this type of drug won’t help. You won't have periods or release eggs while you are having the injections.

LH blockers used for breast cancer are goserelin (Zoladex) and leuprorelin (Prostap, Lutrate). You might have it on its own or with other hormone therapy drugs such as tamoxifen or exemestane.

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 (Faslodex)

Fulvestrant is a hormone therapy for post menopausal women with secondary breast cancer. You may have it if tamoxifen or aromatase inhibitors are no longer controlling your cancer.

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 on its own, or in combination with other drug treatments such as:

• palbociclib

• alpelisib

• ribociclib 

• abemaciclib

Elacestrant

Elacestrant is another type of hormone treatment. It works in a similar way to fulvestrant and stops the oestrogen receptors from working. This stops oestrogen from telling the cancer cells to grow.

Elacestrant is for men or post menopausal women with locally advanced or secondary breast cancer. You might have it if your cancer:

• is oestrogen receptor positive

• is HER2 negative

• has grown after having at least 12 months of hormone treatment and a type of targeted cancer drug called a CDK 4 or 6 inhibitor such as abemaciclib, palbociclib, or ribociclib

• has changes (mutation) in the gene known as ESR1

You have a blood test to check for these ESR1 gene changes.

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 ​general anaesthetic.

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.

Find 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.

Go to the 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. 

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. It is called a depot injection, which means that the drug is slowly absorbed into your body over a period of time.

The injection might be under the skin in your tummy, thigh or arm. Or you might have it into a muscle in your leg or buttocks.

You can have the injections every 4 weeks or 12 weeks.

Fulvestrant

You usually have fulvestrant as an injection into the muscle in your bottom (buttock) once a month. You have 2 injections – one in each buttock.

Elacestrant

You take elacestrant as a tablet once a day. Try to take it at the same time each day, with food. Swallow the tablets whole with a drink. You should not chew, split or crush the tablets.

You should take the right dose, not more or less.

Talk to your healthcare team before you stop taking a cancer drug, or if you miss a dose.

Side effects

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

• tiredness

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.

It is important not to stop your hormone therapy. Talk to your healthcare team if you have any side effects. They may be able to help reduce them.

Bone thinning

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 ​DEXA scan​ first. This is to check your bone strength (bone density).

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.

Find out more about the side effects of hormone therapy

Early menopause

All the treatments that stop your ovaries working give you an early menopause, but this might be temporary. Some women find this very difficult to deal with. You are likely to have menopausal symptoms that start very suddenly.

Read about managing menopausal symptoms