Genetic testing for breast cancer risk

Genetic testing looks for gene abnormalities that increase the risk of cancer. In breast cancer, common mutations (faults) occur in the genes BRCA1 and BRCA2.

Testing can help you make decisions about:

• how to reduce your risk of breast cancer
• what sort of surgery you might want if you have been diagnosed.

About genetic testing

Some genes protect us from cancers. If we inherit an abnormal gene (‘mutation’) from a parent, our risk of cancer can increase.

It is important to remember genetic mutations are uncommon. Only 5-10% of breast cancers are caused by a genetic mutation.

Genetic testing looks for changes in many genes. The aim is to identify if genes are abnormal, and if there is an increased risk of developing breast or other cancers.

Types of genetic test

There are 2 main types of genetic test:

1. Mutation search genetic test

This blood test searches for faults in a number of genes including BRCA1, BRCA2 and PALB2. This fault is linked to causing or increasing the risk of cancer.

Often, testing includes checking other genes connected to cancer, such as ATM, TP53 and CHEK2.

Who may be suitable

It is usually done for a person who has already had a diagnosis of breast or ovarian cancer or both.

How long results take

The results can take several weeks, as the faults are very hard to find. A doctor can ask for a quicker test if a decision about treatment depends on the results.

Cost

Not everyone is eligible for Medicare-funded genetic testing. You are eligible if you meet certain criteria:

• breast cancer diagnosis before the age of 40 
• diagnosis of breast cancer in both breasts ('bilateral') or 2 breast cancers, with first cancer first diagnosed before the age of 50. 
• diagnosis of triple negative breast cancer diagnosed before the age of 60. 
• diagnosis at any age of male breast cancer. 
• the presence of a faulty BRCA1 or BRCA2 would make you eligible for Olaparib (targeted therapy). 

If you fit the criteria, you can have the blood test at a familial cancer service in a public hospital or a private laboratory. 

You may not meet the criteria for publicly funded genetic testing but still want to be tested. The cost is around $400. Medicare and private health insurance do not provide rebates for this test in Australia.

2. Predictive genetic test

If a faulty gene is detected in your family, other members in the family can be tested. This is called predictive testing, and it looks for the same mutation in each family member.

How long results take

The results can take several weeks but it quicker than the test that looks through all the genes. A doctor can ask for a quicker test if a decision about treatment depends on the results.

Cost

The cost for a predictive genetic test is usually covered by Medicare.

How to access a genetic test

Genetic testing can be ordered by:

• a specialist family cancer clinic (e.g. genetics specialist)
• a breast cancer specialist, such as a surgeon, medical oncologist or radiation oncologist.

Your specialist may offer this soon after your diagnosis of breast cancer. This is because the results of genetic testing might change the treatments they recommend.

Understand the results

The test report will say whether a genetic variation (fault or mutation) has been found. For most people, gene testing does not find any mutation.

‘No pathogenic variant’ means no abnormal genes were found. In this case, other family members do not need to think about genetic testing. It means your breast cancer was not caused by a genetic fault, and the cancer risk is likely to be low to moderate for you and your family.

‘Pathogenic variant’ means a genetic mutation was found. This means the variation (mutation) in the gene stops it from working correctly. In this case, other family members will be eligible for genetic testing, whether they have a cancer history or not. Genetic testing is only offered to people over 18 as most breast cancer genes are linked to a risk of cancer in adulthood. If you inherit a gene mutation, your breast cancer risk will be higher than for people without a gene change.

‘Variant of uncertain significance’ means the test found a genetic variant (‘alteration’), but research does not show whether this stops the gene from working. This might be worrying for you. It is important to know that most variants of uncertain significance will not change how the gene works. In this case, genetic testing is not available for family members. A result of ‘uncertain significance’ is more common in people with non-Caucasian ethnicity.

What to do if your risk is high

If you have a breast cancer gene mutation, preventive (‘prophylactic’) treatment options may be available.

Surgery: some people consider risk-reduction surgery such as preventative mastectomy (removal of the breast tissue) with or without breast reconstruction.

Medication: tamoxifen has shown some benefits for people at a very high risk of breast cancer.

You may find it helpful to read about mastectomy surgery. Note that this information is written for people with a breast cancer diagnosis.  

Genetic testing and life insurance

It’s important to know that the results of genetic testing can affect some insurances for you and your family members. This is called ‘genetic discrimination’.

If your life insurance policy started before 1 July 2019 and have been paying your premiums, your genetic test will not affect your current policy. You do not have to let your insurer know the results of genetic testing.

From 1 July 2019 to 30 June 2024, people did not have to provide the results of genetic tests for life insurance, Total & Permanent Disability (TPD) insurance and/or income protection insurance. If you took out a policy before 30 June 2024, you can keep that policy for as long as you pay the premiums.

Since 1 July 2024: The Australian Government announced a ban on genetic discrimination in life insurance, but this legislation has not yet passed (as at March 2025). Currently, there is a risk of discrimination after genetic and genomic testing. BCNA is advocating for this to change.