Definite breast cancer risks
This page tells you about things that can affect your risk of breast cancer. You can find information on
Definite breast cancer risks
Researchers have identified a number of things that can affect your risk of breast cancer. Breast cancer risk increases with age. Your risk is increased if you've had it before, or if someone in your family has. You have a particularly increased risk if you carry a breast cancer gene. A history of some non cancerous breast diseases or having had DCIS or LCIS also increases risk.
Hormonal factors
There are some hormonal factors that increase risk, including having higher levels of hormones in your blood after the menopause, starting periods early and having a late menopause, having no children or having them late in life, and taking hormone replacement therapy (HRT) or the contraceptive pill.
Lifestyle and past medical treatment
There are also some life style factors that increase risk, including your alcohol intake and your body weight. Past medical treatment can affect breast cancer risk, for example exposure to radiation, including treatment for Hodgkin's lymphoma.
Unfortunately you can't do anything about most of these risks, apart from be aware of them. But you can make sure you take advantage of all the health care offered to you, by going for your breast screening tests.
More than 45,500 people are diagnosed with breast cancer in the UK each year. Most of these are women. Only around 300 are men. Breast cancer is now the most common cancer in the UK (excluding non melanoma skin cancer) and by far the most common cancer in women.
1 in 9 women will develop breast cancer during their lifetime. Most of the women who get breast cancer have had their menopause, but almost 8,000 diagnosed each year are under 50 years old.
Like most cancers, the risk of developing breast cancer increases as women get older. Cells have to 'go wrong' to turn into cancer cells. And the longer we are alive, the more time there is for that to happen. Obviously you can't do much about getting older. But you can have mammograms as part of the national breast screening programme as soon as you are old enough. The UK screening programme sends invitations for screening to all women aged between 50 and 70. You won't be invited to come for mammograms once you reach the age of 71, but you can ask your local breast cancer screening office to carry on inviting you every 3 years.
In the UK, women of South Asian origin have a lower risk of breast cancer than the rest of the population. This is probably due to lifestyle factors, such as eating a vegetarian diet and low alcohol consumption.
We know that a woman who has had breast cancer has an increased risk of getting breast cancer in the other breast. Your specialist knows that too and will keep a close eye on you. If you do get a breast cancer in the other breast, it should be picked up quickly. You will have some protection against getting another breast cancer if you are taking hormone therapy to lower the risk of your breast cancer coming back.
If several members of your family have had particular types of cancer, you may have an increased risk of developing breast cancer. NICE (the National Institute for Health and Clinical Excellence) have guidelines that identify family histories that could increase your risk of breast cancer. If you fit these criteria, your GP should refer you to a specialist breast clinic for assessment.
NICE classify women into 3 groups. Under this system, you may have a moderate risk of breast cancer, a high risk or the same risk as the general population of women (a low risk). NICE say that moderate risk means you have at least a 1 in 6 risk of getting breast cancer by the end of your life. When compared to the risk of the general population, you may have some increase in breast cancer risk if you have ONE of the following in your family
- A mother or sister diagnosed with breast cancer before the age of 40
- 2 close relatives from the same side of the family diagnosed with breast cancer - at least one must be a mother, sister or daughter
- 3 close relatives diagnosed with breast cancer at any age
- A father or brother diagnosed with breast cancer at any age
- A mother or sister with breast cancer in both breasts - the first cancer diagnosed before the age of 50
- 1 close relative with ovarian cancer and 1 with breast cancer, diagnosed at any age - at least one must be a mother, sister or daughter
The affected relatives must come from the same side of your family (ie either your mother's side OR your father's side) and they must be your blood relatives. A close relative means a parent, brother or sister, child, grandparent, aunt or uncle, nephew or niece.
These are only guidelines and after assessment by their local breast clinic some women may be told their risk is much the same as the average woman. If your risk is found to be high, the breast team may offer you an appointment with a genetic counsellor to help you understand more about your risk. You will also be offered information about genetic testing.
If your doctor or genetic ounsellor think you have a raised risk of breast cancer and you are between 40 and 49, you will be offered yearly mammograms. If you are over 49, you will be part of the national UK screening programme anyway, and will have mammograms every 3 years. You have mammograms more often if you are younger, because mammograms are more difficult to read in younger women (as the breast tissue is more dense). If you are between 30 and 39, mammograms are only recommended as part of clinical trials into screening. Mammograms are not recommended at all if you are under 30 but you may be offered other types of screening.
The NICE guidelines include recommendations on the use of MRI scans for screening women who are at increased risk of breast cancer. NICE recommends yearly MRI scans if you are
- Aged 20 or older and carry the faulty TP53 gene
- Aged between 30 and 49 and carry the faulty BRCA1 or BRCA2 gene
The guidelines also recommend MRIs each year to women with an increased risk of breast cancer who are
- Aged between 30 and 39 and have more than a one in 12 chance (8%) of developing breast cancer in the next 10 years
- Aged between 40 and 49 and have more than a one in 5 chance (20%) of developing breast cancer in the next 10 years
- Aged between 40 and 49 and a previous mammogram showed a dense breast pattern (giving more than a one in 8 chance (12%) of breast cancer in the next 10 years)
The breast care team work out your risk of developing breast cancer using your family history and individual factors.
You can download a copy of guidance for the public from NICE on the care of women with breast cancer in the family. There is more information about breast screening and who should be referred in this section of CancerHelp UK.
If you are concerned that several members of your family have had breast or ovarian cancer, the best thing to do is talk to your GP. If you like, you could print off this page and take it with you.
If you have a very strong family history, there may be a faulty gene in your family that increases your risk of breast cancer. There are probably several gene faults that can increase breast cancer risk. We can test for 2 of them, BRCA1 and BRCA2. Your risk of getting breast cancer in your lifetime if you have either of these breast cancer gene faults could be as much as 85%. Half of all women (50%) who carry a faulty breast cancer gene will have developed breast cancer by the time they are 50 years old.
We say 'up to' 50% or 85% because the actual risk varies between families. Having one of these faulty genes means that you are more likely to get breast cancer than someone who does not carry the gene fault. But it is not a certainty. Genes for any characteristic do not always show up in an individual person. This is called gene expression or penetrance. The breast cancer gene BRCA1 is known to be highly penetrant. This means that it shows up at some time in up to 85 out of every 100 of people who have it. But its activity can be affected by other genes that you carry, or by any other breast cancer risk factor, such as lifestyle or environmental exposure to other carcinogens.
It is also possible to test for the faulty TP53 gene and PTEN gene, which are much rarer than BRCA mutations, but can increase the risk of breast cancer. Rare gene changes that can slightly increase the risk of breast cancer include CHEK2, ataxia telangiectasia mutated gene(ATM), BRIP1, and PALB2. More common gene changes that increase breast cancer risk by a very small amount include FGFR2, TNRCP, MAP3K1, and LSP1.
Remember that most breast cancers happen by chance. Only about 5 out of every hundred are related to a known inherited breast cancer gene. The older you or your relatives are when diagnosed, the less likely it is that an inherited gene is the direct cause. There is more information about breast cancer genes, getting tested and your options if you carry a gene in this section of CancerHelp UK.
The female sex hormone, oestrogen, and the male hormone, testosterone, can affect the development of breast cancer. Women tend to have small amounts of the male hormone testosterone in their bodies. Studies generally show that after their menopause women with higher levels of oestrogen and testosterone in their blood have a 2 to 3 times higher risk of breast cancer than women with the lowest levels of these hormones. Before the menopause, levels of oestrogen vary during the menstrual cycle and studies have not shown clearly that these hormones affect the risk of breast cancer in this group of women. Many of the major risk factors for breast cancer can be explained through their effect on hormone levels.
Starting your periods (menarche) at an early age has been linked with an increased risk of breast cancer. And if you have a late menopause this increases your breast cancer risk.
Women who have children have a slightly lower risk of breast cancer than women who don't have children. And the younger you are when you have your first child, the lower your risk of breast cancer.
Until recently, many doctors thought that the benefits from HRT outweighed the risks. But then a US research study was stopped because there seemed to be much too big a risk of heart disease and stroke in the group of women taking HRT. In 2003, researchers from Cancer Research UK looked specifically at HRT and risk of breast cancer. They showed, for the first time, that combined HRT (oestrogen and progesterone) is more likely to cause breast cancer than oestrogen only HRT. Before this study was published, experts thought that oestrogen only HRT was riskier. This study recruited over a million women.
So far, the study has only followed the women for up to 4 years. But the researchers estimate that there are likely to be about 5 extra breast cancers for every 1,000 women who take oestrogen only HRT for 10 years. This compares to their estimate of about 19 extra breast cancers diagnosed in every 1,000 women taking combined oestrogen and progesterone HRT for 10 years. The good news for women already on HRT is that your risk seems to go back to normal within 2 to 5 years of stopping taking it.
An American study published in May 2006 in the Archives of Internal Medicine looked at oestrogen only HRT. These researchers say that breast cancer risk becomes more significant after 20 years of oestrogen only HRT. This paper estimates a 40% increase in risk, which would mean about 14 extra breast cancers in 1,000 women after 20 years of oestrogen only HRT.
Using HRT to manage menopausal symptoms is a very personal decision. You need to talk it through with your GP. It may lower your risk of other conditions, such as osteoporosis. But it was disappointing to see in the million women study and US study that HRT may actually increase the risk of heart disease as well as breast cancer.
Other research shows you may increase your breast cancer risk even more if you drink high amounts of alcohol while you are taking HRT.
The combined pill contains oestrogen. Oestrogen can stimulate breast cancer cells to grow. In theory, taking extra oestrogen could trigger a breast cancer to develop. Several large studies have looked at whether the pill can increase the risk of breast cancer. The overall picture seems to be that there is a small increase in risk while you are taking it. But the increase in risk goes back to normal 10 years after you've stopped taking it. Balanced against this, the pill also seems to reduce the risk of some other cancers, such as ovarian cancer.
The research into the contraceptive pill and breast cancer risk is outlined below. Several research studies have shown an increase in the risk of breast cancer while women take the pill and for a while afterwards. But 10 years after stopping the pill, the risk is back to that of a woman who has never taken it. However, a recent large UK study by the Royal College of GPs looked at 47,000 women and showed no increase in the risk of breast cancer in women taking the contraceptive pill. However, many different types of contraceptive pill were used by the women in this study and some were older types of pill. So it is difficult to apply the results to women taking modern types of the pill.
The pill has changed a lot over the years. It used to contain more oestrogen and progesterone than it does now. So older types of pill may have a different effect on breast cancer risk. In the UK, the older style higher dose pills came off the market about 30 years ago. A few research studies have looked at different types of pill to see how they affect breast cancer risk but they have not come to any firm conclusions. One study found a higher breast cancer risk with the older style pills but this is only one study and we need more research before we can be sure.
We don't really know if taking the pill increases the risk of breast cancer for women who have a family history. Some research says it may increase breast cancer risk in these women. Other studies have found that it makes no difference. So we need more research to find this out.
It can be difficult to make sense of all this research. It is important to remember that breast cancer is rare in young women - the age groups most often using the pill are women in their late teens, twenties and early thirties. So a small increase in this risk during the time women take the pill means very few extra cases of breast cancer.
There are 3 types of non cancerous (benign) breast conditions
- Non proliferative
- Proliferative without atypia
- Proliferative with atypia (atypical hyperplasia)
Breast disease that is not growing and where the cells are not dividing is called 'non proliferative' and does not usually increase the risk of breast cancer. But if you have a strong family history of breast cancer it may increase the risk by a small amount.
Breast lumps with an overgrowth of cells (proliferation) but without abnormal (atypical) cells increase the risk of breast cancer by between 1.5 and 2 times the average risk.
About 1 in 20 breast lumps (5%) show 'atypical hyperplasia'. This means the cells are not cancer, but are growing abnormally. Atypical hyperplasia increases your risk of breast cancer by more than 4 times the average. Atypical hyperplasia is uncommon and if you haven't been told that your breast lump showed these changes, it probably didn't. But if you are worried, you can ask your doctor to check the biopsy result and let you know.
You should always get breast lumps checked out immediately to make sure they are not cancer.
Breast tissue density relates to how your breast tissue shows up on a mammogram. Women with dense breast tissue have less fat and more breast cells and connective tissue in their breasts. Because they have a greater proportion of breast cells, the risk of breast cancer is higher. A recent overview of studies (meta analysis) reported that women with the most dense breasts had five times the risk of breast cancer of women with the lowest density. There is some evidence that ultrasound can be a useful test alongside mammography for diagnosing breast cancer in women with dense breasts. Breast ultrasound may be able to pick up a breast cancer that a mammogram has missed. MRI scans may also be helpful in finding cancers in denser breast tissue in younger women.
Alcohol intake has been linked to breast cancer. A large study looked at about 80% of the worldwide research on alcohol. They found there was an increase in risk of breast cancer with the amount of alcohol that women regularly drink. There is an increase in risk of breast cancer of about 7% with each additional daily measure - for example, a glass of wine. This means there will be about 3 extra cases of breast cancer for every 200 women who have 2 drinks a day, when compared to women who don't drink at all. There is information about research into alcohol and breast cancer in the questions and answers section of CancerHelp UK.
Some research suggests that alcohol increases your breast cancer risk even more if you are taking HRT. To be on the safe side, you should not drink more than 14 units of alcohol per week. One unit is a half pint of beer, a glass of wine or a measure of spirits.
These can both affect your breast cancer risk.
Weight is a bit confusing. If you are overweight before you've had your menopause, your risk of breast cancer is lower than average. But if you are overweight after menopause, your risk of breast cancer is higher than average. This is because women who are overweight ovulate less than average. So their breast cells may be exposed to lower levels of oestrogen. But once you are post menopausal, your oestrogen levels are linked to the amount of body fat you have. The more fat, the higher your oestrogen levels are likely to be.
Having said that, we don't recommend that pre-menopausal women should become overweight! That brings many other health problems, such as high blood pressure, diabetes and arthritis.
Taller women have an increased risk of breast cancer. It's not clear why this is, but taller women may have more breast tissue, which might increase the risk.
DCIS stands for ductal carcinoma in situ. This is when breast cancer cells are completely contained within the breast ducts and have not started to spread into the surrounding breast tissue. It is sometimes called pre-invasive breast cancer. LCIS stands for lobular carcinoma in situ. It means there are some abnormal cells in the lobules of the breast.
Studies show that women with a diagnosis of DCIS or LCIS have a risk of invasive breast cancer in the same or other breast between 3 and 7 times higher than women in the general population. One study showed that women with a previous carcinoma in situ of the breast have a 16% (about 1 in 6) risk of developing breast cancer within 10 years. But, even so, most women with LCIS or DCIS will not develop cancer. High grade DCIS or a type of LCIS called pleomorphic LCIS are more likely to develop into breast cancer than other types of DCIS or LCIS. If you do have LCIS or DCIS, your doctor will want you to have check ups regularly afterwards. There is more about LCIS and DCIS in this section of CancerHelp UK.
Exposure to radiation is known to increase the risk of many types of cancer. But most of this research has been in people who have been exposed to a lot of radiation, due to an atomic bomb explosion or a radiation accident. There is known to be a slight increase in risk in people who work with low doses of radiation over a long period of time - for example, X-ray technicians. But most of us would never be exposed to enough radiation to make much difference to our risk.
Nowadays, doctors try to keep medical exposure to radiation as low as possible. They don't do X-rays or CT scans unless they really need to. And the amount of radiation used to take an X-ray or scan is very small, and lower than it used to be. If you had a lot of chest X-rays in the past and are worried, talk to your doctor.
Many women worry that having mammograms exposes them to X-rays. The amount of radiation used to take a mammogram is very small. We can't say it doesn't increase risk, but the increase in risk is tiny compared to the benefit of finding and treating a breast cancer early. Many things we do expose us to slight increases in radiation (such as flying in a plane) but we don't always think it sensible to stop doing them.
If you had radiotherapy to your chest for Hodgkin's lymphoma in the past, you could be at increased risk of getting breast cancer. This applies to all women treated as children or in their 20s. The radiation affects your breast tissue. There probably isn't an increase in risk for the first 5 or 10 years after your Hodgkin's treatment. But there is after that. If you need radiotherapy for Hodgkin's lymphoma you will be told about this risk and offered breast screening if it is appropriate. There is more detailed information about breast cancer risk after Hodgkin's in our questions and answers section.
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