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Between 5 and 10% of all breast cancers| are thought to be due to a strong hereditary predisposition. This means that most breast cancers (9 out of 10) happen without a strong family history of breast cancer.
About 1 in 8 women in the UK develop breast cancer. We don’t know the cause of most breast cancers, but we do know that some things, called risk factors, can increase your chances of developing cancer. Some risk factors are very likely to cause cancer, whereas others will only slightly increase your likelihood of getting it.
Having a particular risk factor| for cancer, or being exposed to one, doesn’t mean that you will definitely get cancer - just as not having it doesn’t mean that you won’t.
We have information about the symptoms of breast cancer|.
Genes carry the biological information we inherit from our parents. They affect the way our bodies grow, work and look. Changes (mutations) in certain genes can increase the risk of breast cancer in family members who inherit the genetic change. However, only a small number of breast cancers (5-10%) are thought to be due to an inherited altered gene (genetic mutation) running in the family.
Changes in two genes - called BRCA1 and BRCA2 - are know to increase the risk of breast and ovarian cancer. Rarely, one of these genetic changes runs in a family, and members of the family who inherit the mutated gene have an increased risk of these cancers.
Only a small number of breast cancers are thought to be due to an inherited altered gene running in the family.
You won’t normally be offered genetic testing if you have only one close relative with breast cancer. But if a genetic counsellor or specialist thinks a susceptibility to breast or ovarian cancer may run in your family they may offer you genetic testing|.
If your family history suggests a high risk of breast cancer in your family, but you decide not to have the genetic test, you and all female blood relatives will usually be offered regular breast screening from the age of 40|.
If you only have one middle-aged or elderly relative who has developed breast cancer, or if there is just one case of breast cancer on each side of your family, this may not significantly increase your risk.
A genetic mutation that could increase your risk of breast cancer is only likely to be present in your family if you have:
If any of these apply to you and you’re worried about your risk of developing breast cancer, you may want to talk to your GP.
BRCA gene changes may be more common in certain populations. If you have relatives with breast or ovarian cancer, and have Jewish ancestry or come from another ethnic background (Icelandic, Dutch or Norwegian) where BRCA gene changes are more common, you may want to discuss your risk with your GP. If they think you may have an increased risk of developing breast cancer because of your family history, they will refer you to a genetic counsellor|, family cancer clinic or a cancer specialist.
Women who are likely to have an increased risk of developing breast cancer because of their family history may be offered additional breast screening. This may involve yearly mammograms (breast x-rays) from the age of 40 and sometimes MRI scans from an earlier age. All women aged 50 and over are automatically invited to join the NHS Breast Screening Programme|, and offered a mammogram every three years until they are 70.
We have an online tool you can use to assess your risk of developing breast or ovarian cancer. OPERA (Online Personal Education and Risk Assessment) is an interactive program that will offer you personalised information and support about your inherited cancer risk. Visit macmillan.org.uk/opera for more details.
All women have some risk of developing breast cancer in their lifetime. But, most women don’t get breast cancer and even if you are told you have an increased risk it doesn’t mean you’ll definitely get breast cancer.
If there is a history of breast cancer in your family your doctor or genetics specialist will assess how this might affect your risk of developing breast cancer over your whole lifetime. They will also assess your risk of developing breast cancer by a certain age. Doing this will help them to recommend the level of care (such as screening| and risk-reducing surgery|) that is most appropriate for you.
Women who have a significantly higher risk of developing breast cancer compared with women in the general population are classified into two groups:
Risk factors other than family history can play a more important role in the development of breast cancer.
Breast cancer mainly affects older women. In the UK, more than half of breast cancers occur in women over 65. Women under 50 are at a far lower risk of getting breast cancer than older women, and the risk is even lower for women under 40.
Your exposure to the hormones oestrogen and progesterone can affect your breast cancer risk. This means you may be at an increased risk of developing breast cancer if you:
Non-cancerous breast conditions are common and most don’t affect your risk of breast cancer. But, a few can increase your risk. They include:
These conditions may be discovered during tests to investigate a breast lump or during routine breast screening. If you have a breast condition that may increase your risk, your doctor can tell you if you need treatment or more frequent breast screening.
If your breasts have more glandular and connective tissue and less fatty tissue, this will make your breasts appear denser on breast x-rays (mammograms). Dense breast tissue increases your risk of developing breast cancer.
Women who have had radiotherapy to their chest at a young age (under 35), for cancers such as Hodgkin lymphoma, may be at an increased risk of breast cancer may and be offered more frequent breast screening.
Being overweight, particularly after the menopause, increases the risk of breast cancer. This may be because it alters the levels of hormones in the body.
Evidence suggests that regular physical activity reduces your risk of breast cancer.
Drinking alcohol increases your risk of developing breast cancer. The increase in risk is small for women who drink within the recommended guidelines, but it increases steadily the more alcohol you drink.
The European Code Against Cancer recommends that women should drink no more than one unit of alcohol a day to reduce their risk of developing cancer. A unit is half a pint of ordinary strength beer, lager or cider, one small glass (125ml) of wine or a single measure (25ml) of spirits.
Some cancer risk factors, such as age and family history, are beyond your control. But, there are some risk factors you can control, known as lifestyle risk factors.
About 1 in 4 cancers diagnosed in the UK (25%) could be avoided if people made changes to their lifestyles.
There are a number of things that you could consider to reduce your risk| of cancer.
This means knowing what is normal for you and what is a serious change. When it is found early, breast cancer can often be treated successfully.
In most cases, changes to your breasts don’t mean that you have cancer but you should see your GP if you have any of the possible symptoms of breast cancer|.
Breast screening can help detect breast cancer early, when it’s easier to treat.
See our section on breast screening| for more information.
Content last reviewed: 1 April 2011
Next planned review: 2013
For answers, support or just a chat, call the Macmillan Support Line free (Monday to Friday, 9am-8pm)
If you have any questions about cancer, need support or just want someone to talk to, ask Macmillan.
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© Macmillan Cancer Support 2013
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