Results from genetic testing can help guide breast cancer care, but not everyone is an eligible candidate.

Genetic testing for breast cancer involves using a sample of blood or saliva to look for changes in certain genes involved in breast cancer. If you have breast cancer, undergoing genetic testing can help guide treatment decisions and plans for the future.

Here’s what to know about genetic testing if you have breast cancer.

Around 5% to 10% of all breast cancers are thought to relate to genetic mutations. Genetic testing for this disease looks for inherited changes, or mutations, in specific genes linked with breast cancer or other types of cancers. These genes include:

  • ATM
  • BARD1
  • BRCA1
  • BRCA2
  • CDH1
  • CHEK2
  • NF1
  • PALB2
  • PTEN
  • RAD51C
  • RAD51D
  • STK11
  • TP53

Depending on the test provider, testing for cancer genes with expanded panels can cover anywhere from 30 to more than 80 genes. It can identify other organs that may be at risk for cancer, such as pancreatic cancer, ovarian cancer, or melanoma. It can also pinpoint others in a family who may harbor mutations.

Changes in the BRCA1 and BRCA2 genes are two of the most well-known genetic mutations in breast cancer.

Multigene testing includes an evaluation for the BRCA1, BRCA2, and PALB2 genes. These genes have been linked to inherited cases of cancer, and mutations in them can put people at a higher risk of breast cancer as well as other cancers.

If you have breast cancer, undergoing genetic testing can help you and your doctor:

  • guide treatment decisions, as certain targeted therapies can be more effective in treating specific types of genetic mutations
  • consider if enrolling in a clinical trial for new treatments that target specific mutations is right for you
  • understand your long-term outlook and risk of recurrence
  • discuss preventive treatment to help reduce the risk of developing other forms of cancer
  • determine whether other family members may benefit from early testing and screening

The National Comprehensive Cancer Network (NCCN) recommends genetic testing in people with breast cancer under certain circumstances, including:

  • those diagnosed at age 50 or younger
  • those diagnosed at any age and also have a family history of certain breast, ovarian, pancreatic, or prostate cancers
  • those whose treatment choices could be influenced by genetic test results
  • those who have triple-negative breast cancer
  • those diagnosed with more than one breast cancer, and the second cancer isn’t a recurrence
  • those who have lobular breast cancer who also have a family history of stomach cancer
  • those who are of Ashkenazi Jewish (Eastern European) ancestry
  • those assigned male at birth who are diagnosed with breast cancer

Research shows that those with phyllodes tumors of the breast should also get genetic testing.

Your doctor may refer you to a genetic counselor to help you explain which types of tests are available to you and what information they can provide.

Not everyone diagnosed with breast cancer is suitable for genetic testing.

Currently, access to genetic testing is restricted based on your family history and other clinical criteria. However, many people are not offered the testing based on existing criteria. This means those carrying cancer genes are not always given the opportunity to find out if they are carriers.

In fact, only around 33% of those diagnosed with breast cancer meet the guidelines for genetic testing, yet many of them don’t receive it.

The current consensus on whether or not genetic testing should be offered to everyone diagnosed with breast cancer varies:

  • The American Society of Breast Surgeons recommends genetic testing for everyone.
  • The American Society of Clinical Oncology and the Society of Surgical Oncology recommend BRCA1 and BRCA2 screening for those ages 65 and under who are newly diagnosed with breast cancer.
  • The NCCN only recommends genetic testing for those who meet specific guidelines.

One possible reason for this discrepancy is that most individuals who develop breast cancer don’t have an inherited gene mutation linked to their cancer risk.

However, according to a 2019 study, conducting multigene testing on breast cancer patients when they are diagnosed is cost effective and could save thousands of lives.

So it’s important to work closely with your care team to determine if genetic testing would be beneficial for you.

Many breast cancers are not linked to gene mutations. However, genetic testing can help identify your risk for other cancers, determine if targeted therapies are a good option for you, and support screening for family members where appropriate.

While various guidelines disagree on whether everyone who has breast cancer should undergo genetic testing, research suggests that broadening screening requirements could save lives. Working with your doctor can help you decide if genetic screening is right for you.