Genetic testing for altered breast cancer genes

Some people have a higher risk of developing breast cancer because they have inherited an altered gene.

Genetic testing is used to find out whether you have an altered gene. If you do, your family members may also be eligible for genetic testing.

An altered gene may also be referred to as a gene change, fault, variant or mutation.

The most common inherited altered genes that increase the risk of breast cancer are called BRCA1 and BRCA2. BRCA stands for BReast CAncer. 

BRCA1 and BRCA2 genes usually protect us from developing breast and ovarian cancer. However, inheriting an alteration in one of these genes increases the risk of developing cancer.

PALB2 is a gene that normally controls cell growth to help stop cancer developing (known as a tumour suppressor). Inheriting an alteration in this gene may increase the risk of developing breast cancer and some other types of cancer.

Other less common altered genes may also increase the risk of developing breast cancer and other types of cancer.

How common are altered genes?

Around 5 to 10% of women with breast cancer are thought to carry an altered gene.  

Do altered genes only affect women? 

Both women and men can inherit, carry and pass on an altered gene that increases the risk of breast cancer. 

While a man with an altered gene is unlikely to develop breast cancer himself, he can pass the altered gene on to his children. Some altered genes can increase the risk of other cancers, such as prostate cancer, in men.

When thinking about family history of breast cancer, it’s important to consider relatives on both your mother’s and father’s side of the family.

You may be eligible for genetic testing if:

1. You have a significant family history of breast or ovarian cancer
2. An inherited altered gene has already been identified in your family
3. You have at least 1 Jewish grandparent
4. You have or have had breast or ovarian cancer and meet at least one of the following:

• You were diagnosed with breast cancer before the age of 40
• You’ve had breast cancer in both breasts (bilateral) before the age of 60
• You were diagnosed with triple negative breast cancer before the age of 60
• You were assigned male at birth
• Both you and a first degree relative were diagnosed with breast cancer before the age of 45 (first degree relatives include your mother, father, brothers, sisters and your children)
• You have at least 1 grandparent from Westray (Orkney) or Whalsay (Shetland)

Genetic testing is available in the NHS usually through genetics centres for people who have had genetic counselling. 

At some hospitals, you may be offered pre-test counselling and genetic testing by the breast and gynaecology treatment teams.  

Your genetics or specialist team will tell you if genetic testing is an option for you. 

If you’re concerned about your family history, speak to your GP or treatment team. 

Current tests look for alterations in 7 genes. These genes are:

• BRCA1
• BRCA2
• PALB2
• ATM
• CHEK2
• RAD51C
• RAD51D

The NHS Jewish BRCA Testing Programme 

People with Jewish ancestry are more likely to have alterations in the BRCA genes.

If you’re 18 or older and have at least 1 Jewish grandparent, you can have free BRCA testing through the NHS.

If you’re interested in this, you can complete a short form on the NHS Jewish BRCA Programme website. They will contact you with next steps.

Genetic testing and PARP inhibitor treatment

If you’ve been diagnosed with breast cancer, you may also be offered genetic testing to see what treatment options may be suitable for you.

If you have an altered BRCA gene, you could benefit from a type of targeted therapy called PARP inhibitors, depending on what type of breast cancer you have and what other treatment options you’ve had.

Therefore, your treatment team may recommend you have genetic testing to see if you’re suitable for treatment with PARP inhibitors such as olaparib.

Genetic testing and secondary breast cancer

If you have secondary breast cancer, you may be offered genetic testing to see if you’re suitable for treatment with a PARP inhibitor called talazoparib. This testing is usually just for BRCA1 and BRCA2.

ESR1 testing

You may also be offered a test to see if your breast cancer has an ESR1 gene mutation.

As secondary breast cancer cells grow and divide, they develop changes known as acquired gene mutations.

An ESR1 gene mutation is more common in oestrogen receptor positive, HER2 negative secondary breast cancer. It’s more likely to develop if you have been on hormone therapy for a long time. 

These breast cancers can be tested for an ESR1 mutation at the time of growth and spread (progression) of the cancer. This can be done with a blood test.

If the blood test shows your breast cancer has an ESR1 mutation, you may be offered a hormone therapy drug called elacestrant.

If genetic testing is an option, it’s your decision whether or not you choose to have the test. 

Deciding whether to have genetic testing can be a difficult and complex process, and some people who are suitable may choose not to have testing. 

Advantages of having genetic testing

• If you’re found to have an altered gene, you can take steps to manage your cancer risk. For example, you might have regular breast screening or risk-reducing treatment
• It may mean your family members can make choices about having their own risk assessed and managing their risk

Disadvantages of having genetic testing 

• Finding out you have an altered gene may make you feel worried
• Depending on your age, not all risk-management options may be available if you’re found to carry an altered gene
• Depending on your result, your family members may need to decide if they’d also like to be tested

Helping you decide

If you’re having difficulty deciding, your genetics team can support you in making your decision.  

There’s no right or wrong answer. It’s important you have all the information you need to make a decision you feel comfortable with.   

Talking to someone who has had a similar experience can be helpful. Through our Someone Like Me service, you can speak to someone who has had genetic testing.

You may also find it helpful to talk to our nurses by calling our free helpline on 0808 800 6000 or speaking to us online.

If you decide not to have genetic testing, your genetics team will talk to you about managing your risk. Depending on your situation, you may still be offered regular breast screening to check for breast cancer. 

There are 2 stages to genetic testing.

Stage 1: a full screen (diagnostic testing)

The first stage involves testing a relative who has had cancer to try to find out if a known altered gene runs in the family.  

This will usually be a relative who has had breast or ovarian cancer, but it might be a relative who has had prostate cancer. 

Altered genes can be hard to find. There’s a better chance of finding an altered gene in someone who has already been diagnosed with breast or ovarian cancer. 

A blood sample is taken and sent to a laboratory to be tested for known altered genes that increase the risk of breast cancer.   

If you’ve had breast or ovarian cancer and are eligible, you can have the test yourself.

In rare circumstances, if no relatives are available for testing and you have not had cancer, you may be able to have the test yourself. Your genetics team will tell you if this is an option.

The results

Your results will usually be available within 1 to 3 months. You may have a clinic appointment, a telephone call or receive the results in the post. Your genetics team will ask you how you’d like to receive your results.

There are 3 possible outcomes:

A positive result

If an altered gene is found (a positive result), this confirms your chances of developing breast cancer are higher than the general population. You may also have a higher chance of developing other types of cancer.

However, this does not mean you will definitely develop cancer or be diagnosed again if you’ve had it before.

Your genetics team will know which altered gene runs in your family. They can then search for the alteration more easily in other family members, who can be tested to see if they also carry it (predictive genetic testing).

A negative result

A negative result means a known altered gene was not found.  

If an altered gene has not been identified, other family members will not be offered genetic testing.  

However, if you have a significant family history your risk of developing breast cancer may still be higher than the general population. Your genetics team can discuss your individual risk and options for managing your risk.  

A variant of unknown significance (VUS)

In a small number of cases, a variant of unknown or uncertain significance (VUS) may be found. This means an alteration was found in a known breast cancer gene, but it’s not yet known if this particular alteration increases the risk of developing breast cancer. 

Your genetics team will tell you and your family members how to interpret the results of this first test.

Stage 2: a predictive genetic test (targeted genetic test)

If an altered gene is found in 1 family member during the full screen, other blood relatives can be tested to see whether they also carry the identified altered gene. 

This is called “cascade testing”.

The results

The results of a predictive genetic test usually take around 2 to 6 weeks.

Whatever the results of your test, it’s important to talk through any questions or concerns about your results with your genetics team. 

If you do not have an altered gene

If the predictive genetic test shows you do not have the altered gene that was found in your family (a negative result), your risk of developing breast cancer will be the same as people in the general population.

This also means any children you have, or may have in the future, will not inherit this altered gene. 

If you have an altered gene

If the test shows you have inherited the altered gene found in your family (a positive result), your chance of developing breast cancer, and possibly other cancers, is higher than the general population. 

This does not mean you will definitely develop cancer. 

Your genetics team will discuss what options are available for you to manage your risk. 

The options offered to you may include:

1. Regular breast screening
2. Risk-reducing medication
3. Risk-reducing surgery

Find out more about these options on our Family history of breast cancer: managing your risk page.

You do not have to take up any of these options if you choose not to.  

You’re likely to have many questions, such as how to tell your family and whether to have breast screening or risk-reducing treatment. Your genetics team will support you during this time.

Getting the results of your genetic test can be a difficult and uncertain time. You’ll be offered post-test counselling and your genetics team will be able to support you and talk through your feelings and concerns. 

In recent years, genetic home testing kits you order online and complete at home have become widely available.  

Although these home testing kits look at an individual’s genetic information, what they’re testing for and the level of detail may vary between tests.  

Home testing kits may give you inaccurate information about your risk of developing particular genetic disorders. 

If you have concerns about your family history, you should always speak to your GP.  

Genetic Cancer Alliance has more information on direct-to-consumer genetic testing.

Having an altered gene does not mean you will develop breast cancer, ovarian cancer or related cancers. 

However, you do have a higher risk than the general population.  

General population

During their lifetime:

• 1 in 7 women will develop breast cancer (this is a 14% risk)
• 2 in 100 women will develop ovarian cancer (this is a 2% risk)

BRCA1 

During their lifetime:

• Between 65 and 79 in 100 women with an altered BRCA1 gene will develop breast cancer (this is a 65 to 79% risk)
• Between 40 and 60 in 100 women with an altered BRCA1 gene will develop ovarian cancer (this is a 40 to 60% risk)
• 1 in 250 men with an altered BRCA1 gene will develop breast cancer (this is a 0.4% risk)
• Up to 20 in 100 men with an altered BRCA1 gene will develop prostate cancer (this is an up to 20% risk)

BRCA2 

During their lifetime:

• Between 61 and 77 in 100 women with an altered BRCA2 gene will develop breast cancer (this is a 61 to 77% risk)
• Between 10 and 30 in 100 women with an altered BRCA2 gene will develop ovarian cancer (this is a 10 to 30% risk)
• 4 in 100 men with an altered BRCA2 gene will develop breast cancer (this is a 4% risk)
• Up to 25 in 100 men with an altered BRCA2 gene will develop prostate cancer (this is an up to 25% risk)

Less common altered genes

PALB2 

In their lifetime:

• Between 17 and 53 in 100 women with an altered PALB2 gene will develop breast cancer (this is a 17 to 53% risk). This risk is also affected by how many people in your family have been diagnosed with breast cancer 
• Less than 1 in 100 men with an altered PALB2 gene will develop breast cancer (this is a less than 1% risk)

TP53

In their lifetime:

• Up to 85 in 100 women with an altered TP53 gene will develop breast cancer (this is an up to 85% risk)
• Up to 90 in 100 men and women with an altered TP53 gene will develop any type of cancer (this is an up to 90% risk)

Having an altered TP53 gene is also known as having Li-Fraumeni syndrome.

Moderate risk genes

Moderate risk is higher than the general population. However, it’s still more likely the person will not get breast cancer.

RAD51C or RAD51D

In their lifetime:

• Between 16 and 20 in 100 women with an altered RAD51C or RAD51D gene will develop breast cancer (this is a 16 to 20% risk)
• Between 7 and 10 in 100 women with an altered RAD51C or RAD51D gene will develop ovarian cancer (this is a 7 to 10% risk)

CHEK2

In their lifetime:

• Between 23 and 27 in 100 women with an altered CHEK2 gene will develop breast cancer (this is a 23 to 27% risk)

ATM

In their lifetime:

• Between 21 and 24 in 100 women with an altered ATM gene will develop breast cancer (this is a 21 to 24% risk)
• Between 5 and 10 in 100 men and women with an altered ATM gene will develop pancreatic cancer (this is a 5 to 10% risk)
• Between 2 and 3 in 100 women with an altered ATM gene will develop ovarian cancer (this is a 2 to 3% risk)

Other genes 

Some genetic conditions caused by rare altered genes are also associated with breast cancer.

These include:

• Peutz-Jeghers syndrome (altered STK11 gene)
• Cowden syndrome/PTEN hamartoma tumour syndrome (altered PTEN gene)
• Hereditary diffuse gastric (stomach) cancer syndrome (altered E-cadherin (CDH1) gene)
• Neurofibromatosis type 1 (altered NF1 gene)

If one of these runs in your family, your genetics team will talk to you about your risk of breast cancer.

Information for people with an altered gene

If you have been told you have an altered gene, you may find it useful to read our Family history of breast cancer – managing your risk page.