Genetic testing for breast cancer risk

1. Who will be offered genetic testing?
2. How is the test done?
3. Getting your predictive genetic test results
4. Cancer risks for gene carriers
5. Will my children inherit the gene?
6. Insurance
7. Talking to your family after a positive genetic result 

1. Who will be offered genetic testing?

If you have been assessed as being at high risk of breast cancer, you may be offered genetic testing to find out if you have inherited an altered gene. This is usually known as being a ‘gene carrier’. The most common inherited altered genes are called BRCA1, BRCA2 and TP53.

Your genetics team will tell you if genetic testing is an option for you. Genetic testing will try to find out if there is a known altered gene that runs in your family. If genetic testing is an option for you, it is your decision whether or not to have the test.

In the NHS, genetic testing is usually only available through a genetics centre and after you’ve had genetic counselling. However, at some hospitals pre-test counselling and genetic testing may be provided by the breast and gynaecology specialist teams (for example by the surgeon or oncologist), and if post-test counselling is needed this would be done by the genetics team.

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2. How is the test done?

There are two stages to genetic testing.

Stage one – a full screen (or diagnostic test)

The first stage of testing is to try to find out if one of the known altered genes runs in your family.

Altered genes can be difficult to find and it is much easier to find an altered gene in someone who has already been diagnosed with breast or ovarian cancer.

If you have been diagnosed with breast or ovarian cancer then the test can be done on you. If you haven’t had breast or ovarian cancer and no one in your family who has is available for testing, you may be able to have the test yourself. Your genetic counsellor will be able to tell you if this option is available.

The test involves taking a blood sample and sending it to a laboratory where the DNA (deoxyribonucleic acid) is tested for the known altered genes. The results from this test are usually available within two to three months.

A positive result

If an altered gene is found, your genetics team will then know which one runs in your family and can search for it more easily in other family members (see predictive genetic test below).

A negative/inconclusive result

As it can be hard to find an altered gene, sometimes a genetic test produces a negative/inconclusive result. This means a known altered gene hasn’t been found, but your family history may still be due to an altered gene that hasn’t been identified yet. You will continue to be managed as high risk.

A variant of unknown/uncertain significance

Sometimes the result can show an alteration in one of the known breast cancer genes (BRCA1 or BRCA2), but it is not known if this particular alteration can cause cancer (called a variant of unknown/uncertain significance (VUS)). Your genetics team will advise you and family members how to interpret the results of this first test.

Stage two – a predictive genetic test (or targeted genetic test)

If an altered gene is found in one family member during the full screen/diagnostic test, other blood relatives will be able to have a genetic test to see whether they also carry the altered gene. This is called a predictive genetic test. The result of a predictive genetic test usually takes about four weeks.

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3. Getting your predictive genetic test results

A negative genetic test result

If the predictive genetic test shows that you don’t have the altered gene (a negative result), your risk of developing breast cancer is the same as women in the general population

Having a negative result also means that any children you have, or may have in the future, won’t inherit an altered gene.

A positive genetic test result

If you’ve had a positive result, this means you have inherited an altered gene and your chance of developing breast cancer (and possibly other cancers) is far greater than the general population.

You will be offered regular screening, drug treatment or risk-reducing surgery, but you don’t have to take up any of these options.

You are likely to have many questions such as how to tell your family and whether to have screening or risk-reducing treatment. You will be offered post-test counselling and your genetics counsellor will be able to support you and talk through your feelings and concerns. Find out how Breast Cancer Care can support you during this time.

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4. Cancer risks for gene carriers

Having inherited an altered gene doesn’t necessarily mean you’ll go on to develop breast or ovarian cancer. However, you do have a higher risk than people in the general population. The risks are different for men.

Cancer risks for women who carry a BRCA1/2 gene

Cancer risks for men who carry a BRCA1/2 gene

TP53 gene carrier risks

If you have an altered TP53 gene, the lifetime risk of developing cancer is up to 70% for men and up to 90% for women.

Find out more about age-related cancer risks for gene carriers.

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5. Will my children inherit the gene?

If you have children, there is a 50% chance that they have inherited the altered gene. If you are planning to have children there is a 50% chance they will inherit the altered gene. The risk is the same for boys and girls.

People need to be 18 before any further assessment of their risk of breast cancer can take place.

Find out more about being worried about passing on the gene to future children.

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6. Insurance

Currently, if you’ve had a predictive genetic test for breast cancer you don’t have to disclose the result when you apply for insurance such as life or health insurance (under a certain amount). However, insurance companies do ask about your family’s medical history and if you have a significant family history of breast cancer you may be charged a higher premium. If you’ve had a diagnosis of breast cancer you will have to disclose this and it may be more difficult to get travel insurance. Find out more about breast cancer and travel insurance

If you would like more information, Genetic Alliance UK has produced an information guide on insurance and genetic conditions.

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7. Talking to your family after a positive genetic result

If you’ve had a positive genetic result, it is very important to talk to your family about your result because first degree relatives (such as brothers and sisters and children) will have a 50% chance of inheriting the same altered gene. If they are aware of this they have the chance to make choices about having their own risk assessed and managing any risk.

Your genetic counsellor can help you work out the best way to do this. They may have prepared letters that you can adapt and send to your relatives. You may feel it would be better to tell your relatives face to face, or you may prefer to phone or email them.

Their reactions may vary. It may come as a complete shock to them. Some relatives may choose to ignore the result and may even find it difficult to talk to you afterwards. Others will be glad that you have warned them about the possibility that they may have inherited an altered gene and will then want to have a genetic test themselves.

No one is to blame for the genes they inherit or pass on, but telling your family that they may have inherited an altered gene will give them the option to discuss the possibility of genetic testing and manage their own risk.

Talking to your children after a positive genetic result

Many parents worry about telling their children and it can be difficult to know the right time.

Even though you may find it difficult, talking to your children as soon as you feel ready can be helpful for you both. Children can be quick to pick up on secrets and are less frightened if they know what is happening. If they feel left out they may think they have done something to upset you or they may make up their own story about what is happening. Being open and honest will make them feel valued and help them trust you.

However, you may want to consider your child’s maturity, any other stressful things going on in your child’s life and whether you’ve adjusted to the news yourself yet. When to tell your child is a very personal decision and you know them better than anyone.

Tips for talking to children

  • Children and teenagers usually respond better to informal conversations, often while you are doing things together.
  • Give them small amounts of information at a time, to help them understand at a pace that is right for them. Let them know you will keep coming back to the conversation and that they can too.
  • Depending on their age, children will have a different understanding of genes. Ask them to say in their own words what they think is happening so you can see if they are confused about anything.
  • Children may find it hard to express their concerns or worry about upsetting you. Reassure them that they can ask you anything and, if they do ask a question, make sure you have understood why they are asking it.
  • If you don’t have an answer to a question, explain that you don’t know or that you will try to find out.
  • Include positive messages about what can be done now you know you have inherited an altered gene, and let them know that children and young people are not at risk and they have just as much chance of not inheriting the gene.

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Last reviewed: March 2017
Next planned review begins 2019

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Please note that we cannot respond to comments. If you have any questions about breast cancer please contact the Helpline on 0808 800 6000.