THE HORMONE OESTROGEN (or ‘estrogen’ in the USA, hence ‘ER-positive’) can stimulate the growth of some breast cancer cells. If you haven’t gone through the menopause, you produce oestrogen in your ovaries. If you’ve had your menopause, or if you’re a man, you still make some oestrogen in your body fat by converting other hormones using an enzyme called ‘aromatase’.
As we said in Chapter 3, every breast cancer is tested to see whether it has oestrogen receptors. This is normally done from your core biopsy. An ER-positive (ER+ve) cancer has oestrogen receptors and is sensitive to oestrogen (about 85 per cent of all breast cancers worldwide). Liz’s cancer was ER-positive, while Trish’s was ER-negative. If you have an invasive ER-positive cancer, lowering the amount of oestrogen in your blood should stop your cancer growing and reduce the risk of it coming back in the future. If you have DCIS, you do not need this treatment because your cancer is non-invasive.
There are two ways to lower the amount of oestrogen in your body or the effect it has on your cells – hormone therapy and ovarian suppression – and these are discussed below.
‘Hormone therapy’ means taking drugs to block the effects of oestrogen on breast cancer cells (like tamoxifen) or to stop you making oestrogen in your body fat (like an Aromatase Inhibitor).
Tamoxifen stops oestrogen attaching to breast cancer cells so they are no longer stimulated to grow. It is given to pre- and post-menopausal women with both primary and secondary breast cancer. Tamoxifen is a tablet that you take every day but it also comes as a liquid if you can’t swallow tablets. It can harm your baby if you become pregnant, so you must use contraception while you are taking it.
Faslodex (fulvestrant) attaches to the oestrogen receptors and stops them working. It also reduces the number of receptors in the cancer cells. It is given to post-menopausal women with secondary breast cancer whose cancer has progressed on other hormone therapies. It is given every two to four weeks as an injection in each buttock.
Aromatase Inhibitors (AIs) stop the enzyme aromatase making oestrogen in your body fat which lowers the amount of oestrogen in your body. They are given only to women who are post-menopausal with either primary or secondary breast cancer. If you are pre-menopausal, your ovaries are still producing oestrogen and therefore the AIs won’t be anywhere near as effective for you.
There are three AIs, and they are all tablets that you take once a day:
1. Anastrazole (Arimidex)
2. Letrozole (Femara)
3. Exemestane (Aromasin)
You start taking hormone therapy when you have finished your chemotherapy and surgery. There are some research studies looking at the effect of giving hormone therapy before surgery, and your oncologist may talk to you about this if you are eligible to enter a trial. There is also some new evidence that some people could benefit from having hormonal therapy for several months before breast cancer surgery, but this is not currently done in the UK.
If your doctor doesn’t think you are fit enough to have an operation and your cancer is ER-positive, they can treat you with hormonal therapy only. The aim is that it will shrink your cancer, or at least stop it growing. If it does start growing again, they may change you to a different tablet or reconsider surgery.
We know that ER-positive breast cancer can come back after 10 or even 20 years. That is why you take hormone therapy for a long time. At the time of writing, if you have a low risk of recurrence, you will be advised to take hormone therapy for five years. If you have a higher risk of recurrence and are taking tamoxifen, recent trials have shown that taking it for another five years (ten years in total) further reduces the risk of your cancer coming back. The evidence is less clear if you are taking an AI. There may be some benefit in taking an AI for another two years (seven in total) or switching to tamoxifen for a further five years of treatment. Your doctor will see you in clinic after five years of treatment and advise you whether you need to stay on hormonal therapy, and how long for. New research findings are emerging all the time, so be prepared for the recommended time periods to change in the future.
Hormonal contraceptives (birth control pills and implants) and HRT (hormone replacement therapy) usually contain oestrogen. If your cancer is ER-positive, this oestrogen could stimulate it to grow and stop the hormone therapy from working. If you are currently taking the contraceptive pill or have an implant, you will need to switch to another form of contraception, such as a condom, cap or coil (see Chapter 17). If you are currently taking HRT, you must stop taking it before you can start hormone therapy.
QUESTIONS TO ASK YOUR DOCTOR
● Do I need hormone therapy?
● Will it improve my survival from breast cancer?
● How long will I need to take it for?
● Can I carry on taking HRT (hormone replacement therapy)?
● Can I still use the oral contraceptive pill or implant for contraception?
● What are the side effects?
● What happens if I can’t cope with the side effects?
● Can I stop taking hormone therapy if I want to?
If you are pre-menopausal, your oncologist may discuss stopping your ovaries working to further reduce the amount of oestrogen in your body and decrease the risk of recurrence. This also means that they can give you an AI, which might be more effective for your particular type of cancer. There are two ways to switch off your ovaries: drugs (like Zoladex) are used to stop your ovaries working, or you have an operation to remove your ovaries.
Goserelin (Zoladex) is a drug that blocks the hormone that stimulates your ovaries to produce oestrogen. This means that you won’t have periods any more, and will experience a sudden, early menopause. We explain this in more detail and tell you how to cope with menopausal symptoms in Chapter 16. Goserelin is given as a monthly injection into your tummy fat, just below the skin, either by a nurse in the hospital or a nurse in your GP surgery. Some patients may be able to eventually do it themselves. It is quite a large needle and can be uncomfortable or even painful to have, but the pain only lasts for a second or two. You may be offered an anaesthetic cream to put on the skin at home to help numb the area first. You’ll be a little bruised and sore afterwards, and may notice a bit of bleeding at the injection site, but this is normal and nothing to worry about. The side effects of Goserelin are similar to the AIs (see here). When you stop Goserelin, your ovaries should start to work again.
Surgical removal of the ovaries is a permanent way to stop oestrogen production, and if you have this you will have a sudden, early menopause. If you have the BRCA gene (see here), you will be advised to have this operation once you are in your forties to stop you getting ovarian cancer. It is a keyhole operation with a general anaesthetic where the surgeon uses a camera connected to a screen to look inside your tummy, and uses small instruments to remove your ovaries. You will be left with a few small scars low on your tummy, and one in your belly button where the camera goes in.
QUESTIONS TO ASK YOUR DOCTOR
● Do I need ovarian suppression?
● Will it improve my survival from breast cancer?
● What is the difference between an injection and surgery?
● What are the side effects?
● Is it reversible?
All of the therapies above have a large number of potential side effects, mainly menopausal, which most of you will experience to a certain degree. They tend to get better over time, generally within a year of starting the therapy.
With hormonal therapy, some patients say that one brand of tablet gives them fewer side effects compared to another. If you are finding it hard to cope, you could ask your pharmacist to order you a different brand to try. We know that some patients don’t take their tablets regularly because of the side effects, but few of them admit this to their doctor. We do understand that the side effects can be hard to deal with, and Liz still struggles with some of them. However, if you don’t take the tablets, you are increasing the chance that your cancer might come back in the future.
If you are struggling with the side effects, please talk to your doctor before discontinuing. They can use the PREDICT tool (see here) to calculate your individual benefit from hormone therapy. If it is very small, maybe 1–2 per cent, this means that if 100 women have hormone therapy, only one or two of them will live longer because of it, and this might make it easier for you to decide to stop taking your tablets. However, if your estimated benefit is much greater, say 5–10 per cent, you might decide it is worth coping with the side effects to reduce the risk of your cancer coming back.
You may not have any menopausal symptoms, especially if your own menopause was some time ago. However, it can be completely different if you are pre-menopausal and suddenly thrown into an instant early menopause, like Liz was. One day Liz was ‘normal’, and the next she was stripping off in supermarkets and waking up in the middle of the night thinking she had wet herself, thanks to hot flushes and night sweats. It was a huge shock to the system, and it took her several months to get used to it. We talk about menopausal symptoms and, more importantly, how to cope with them in Chapter 16.
If you have had ovarian suppression or are taking an AI, you may be at risk of osteoporosis (bone thinning). This is discussed in more detail here.
A rare but potentially fatal side effect of hormone therapy is developing a blood clot in a vein in your leg (DVT or Deep Vein Thrombosis). This starts as a painful, swollen calf and you should see your doctor urgently if you develop this. If it’s not treated, the clot can spread to your lungs (PE or Pulmonary Embolism). This causes chest pain and shortness of breath and is very serious. If you need to have an operation in the future, you must tell your surgeon that you are taking hormone therapy, because an operation can cause a DVT. They will probably ask you to stop taking it for two to four weeks before your operation to reduce the risk of you getting a blood clot after the surgery.
Hormone therapy can raise your blood pressure and the cholesterol level in your blood. If you already have a high blood pressure or a high cholesterol level, you should ask your GP whether you need extra monitoring or treatment.
Low oestrogen levels can make you hold on to water in your tissues. About 1 in 10 women develop swollen ankles, legs and fingers. You may also get cramps in your legs. Regular exercise and support socks/tights can help, but you may have to tolerate swollen legs for the duration of your treatment.
This is a condition characterised by tingling, weakness and (occasionally) pain in your hand. It is caused by fluid build-up in the tissues at your wrist which causes a nerve to become squashed. It is normally treated with a wrist support. If this doesn’t work you may need a steroid injection or a small operation to fix it.
Your hair may start to thin. Be gentle with it, brush and comb it gently, and try to avoid using hair straighteners and curling tongs. It should go back to normal once you stop taking hormone therapy.
The following side effects can also occur with tamoxifen:
● Endometrial cancer: Tamoxifen can thicken the lining of your womb (endometrium), which can give you unexpected vaginal bleeding or pain, and you may need to have treatment for it. Very rarely, the thickening can develop into a cancer of your womb. If you do get unusual bleeding, you should see your GP to get it checked out.
● Stomach problems: You may get indigestion or feel slightly sick when you first start taking tamoxifen. This normally gets better in time.
● Eye problems: Rarely, tamoxifen can cause blurring of your vision (a cataract), changes in your eyesight or changes in the back of your eye. You should tell your optician that you are taking tamoxifen – they may recommend an eye test every year.
The following side effects can also occur with AIs:
● Joint and muscle pain: This is one of the most common side effects. Most people have pain in the joints of their fingers, hands and feet, and this may be worse if you already have arthritis. The pain can normally be controlled with paracetamol, but you may need to switch to tamoxifen if it doesn’t get any better.
● Headaches, nausea, vomiting and loss of appetite: You may experience some or all of these, and they usually get better with time. Paracetamol can help with the headaches. If you can’t cope with feeling sick, your GP may be able to give you a tablet to help. Try taking your tablets with or after food and eat small, frequent meals and snacks.
● Dizziness. This is a rare side effect. If you feel dizzy, you shouldn’t drive. It normally gets better in time, but if it doesn’t, you should see your GP.
Oestrogen strengthens your bones. After the menopause, when your ovaries stop producing oestrogen, your bones start to weaken and thin. This is called ‘osteoporosis’. When you have an AI or ovarian suppression, this can increase the rate at which your bones thin, because you have less oestrogen. If your bones remain weak, you are more likely to break your bones (e.g. your wrist, hip or spine) if you have a fall. Tamoxifen doesn’t have the same effect because it doesn’t lower your levels of oestrogen; it just stops it attaching to breast cancer cells.
Before you have either an AI or ovarian suppression, you will have a bone density (DEXA) scan to measure your bone strength. This is a very quick scan which involves lying on a table while an X-ray is taken of your back and one of your hips. The DEXA scan is normally repeated every couple of years while you are on treatment.
Your DEXA scan produces a T-score and a Z-score. The T-score compares your bone strength with that of a healthy young adult. The Z-score compares your bone strength with an average person of your age. If your scores are low, it means that your bones are weaker than an average person, and you need treatment to help stop them thinning further.
Your bones rely on calcium to stay strong, and your body needs vitamin D to be able to use the calcium in your diet. You make vitamin D when you are out in the sun, but you might not make enough if you spend a lot of time indoors or live in a country where there isn’t a lot of sunshine. Most people get enough calcium in their diet from dairy foods, green vegetables, soya products and tinned fish. Your doctor may recommend that you take a daily calcium and vitamin D supplement to help keep your bones strong. You should cut down on caffeine and alcohol and try to stop smoking, as all of these can weaken your bones.
Regular weight-bearing exercise is really important to help keep your bones strong. It is why most active people don’t get osteoporosis when they are older. Weight-bearing exercise is when you support your own body weight, for example walking, climbing the stairs, running, aerobics and tennis, but not swimming (see Chapter 18 for more on this).
A bisphosphonate (such as Alendronate or Fosamax) is a drug that strengthens your bones. If you are taking an AI, you may be advised to take a bisphosphonate as well to stop your bones thinning. There is also some new evidence to show that bisphosphonates can reduce the risk of getting recurrent breast cancer in your bones, so your doctor may advise taking it even if you are not on an AI.
You must see your dentist before you start taking bisphosphonates, especially if you need to have teeth extracted or major dental work done. Bisphosphonates can weaken your jaw bone, and there is a very, very small chance that your jaw bone might not heal after dental surgery and could even start to die. This is very difficult to treat, but it is rare.
Bisphosphonates are normally given as a tablet which you take either every day or once a week. Your stomach has to be empty before you take it, so you take it either first thing in the morning before you have had anything to eat or drink, or at least six hours after you last ate or drank. Because the drugs can damage the lining of your gullet, you then have to stay sitting upright or standing for at least half an hour after you have taken them, and wait at least half an hour before having anything else to eat or drink, or taking any other tablets. If you are struggling to take the tablets, your doctor may be able to prescribe you a bisphosphonate injection instead, which is given either monthly, three- or six-monthly.
As you can see, hormone therapy and ovarian suppression have a lot of side effects that many people have trouble dealing with. However, there is a lot of evidence that proves they greatly reduce the risk of your cancer coming back. You should now understand why it is so important to have this treatment, and we hope we have reassured you that the side effects do get better in time. If you are struggling to cope, please talk things through with your doctor.