By Michael R. Grigsby, Editor | Somerset-Pulaski Advocate
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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.
What does genetic testing look for?
Around 5% to 10%Trusted Source 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: Pathogenic variants in ATM are associated with an increased risk of breast, ovarian, pancreatic, and colorectal cancer.
- BARD1: Associated with a higher risk of developing breast cancer, potentially with a predisposition to triple-negative breast cancer. Studies also suggest a moderate risk of triple-negative breast cancer associated with BARD1 mutations.
- BRCA1 and BRCA2: These are considered high-penetrance genes and are the most common cause of hereditary breast and ovarian cancer syndrome (HBOC). They also increase the risk of other cancers like pancreatic and prostate cancers, as well as melanoma.
- CDH1: Mutations in CDH1 are associated with an increased risk of breast cancer, particularly lobular breast cancer, and gastric cancer.
- CHEK2: Considered a moderate-penetrance gene, it is linked to an increased risk of breast cancer, colorectal cancer, and potentially other cancers.
- NF1: Mutations in NF1 can lead to an increased risk of various tumors, including those associated with Neurofibromatosis type 1.
- PALB2: Considered a high-penetrance gene, pathogenic variants in PALB2 significantly increase the risk of breast cancer, with some studies estimating a lifetime risk exceeding 30%.
- PTEN: Pathogenic variants in PTEN are associated with Cowden syndrome, which increases the risk of breast, thyroid, and endometrial cancers.
- RAD51C and RAD51D: These genes are associated with moderate risks of breast cancer and ovarian cancer.
- STK11: Pathogenic variants in STK11 are associated with Peutz-Jeghers syndrome, which is linked to an increased risk of various cancers including breast, gastrointestinal, and lung cancers.
- TP53: Mutations in TP53 are linked to Li-Fraumeni syndrome, a rare hereditary disorder associated with an increased risk of developing several types of cancer, often at a young age.
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Importance of genetic testing and counseling
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 there's a personal or family history of cancer, genetic testing for these genes may be recommended to assess risk and guide screening and management decisions. Inheriting a mutation in one of these genes increases the risk of cancer, but it doesn't guarantee the disease will develop. Genetic counseling can help individuals understand their risks, interpret test results, and explore personalized risk reduction strategies.
Benefits of genetic testing in breast cancer
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
Who should get genetic testing?
The National Comprehensive Cancer Network (NCCN) recommends genetic testing in people with breast cancer under certain circumstances.
- 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.
Why doesn’t everyone with breast cancer undergo genetic testing?
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 allowed to find out if they are carriers. 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 essential to work closely with your care team to determine if genetic testing would be beneficial for you.
Takeaway
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 proper for you.
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