Breast Cancer Genetic Testing: What It Is, Who It’s For, and Why It Matters

Learn about genetic testing for breast cancer and explore BCRF’s role in funding lifesaving research on cancer genetics.

Genetic testing for breast cancer analyzes a person’s DNA from a blood or saliva sample to determine if they have certain hereditary gene mutations that put them at a higher risk for breast cancer. Specifically, genetic testing looks for mutations in genes that affect how cells normally control growth or repair DNA. While having a mutation does not mean a person will get cancer, it can significantly increase their lifetime risk of the disease. Some mutations may also increase the risk for other types of cancer. This is why genetic testing can help guide overall cancer screening and prevention, not just breast cancer care.

Genetic testing for breast cancer developed once scientists discovered that mutations in BRCA1 and BRCA2 genes — which are involved in DNA repair — can increase breast cancer risk and be passed down through families (i.e., inherited). Since a person’s DNA comes from both parents, if either carries a mutation in their DNA, their offspring may too. This applies to other known breast cancer susceptibility genes identified through sequencing DNA or the entire genome. Through these studies, researchers have spotted gene-specific changes in DNA sequences and correlated those changes with breast cancer. While the most commonly tested genes are BRCA1 and BRCA2, the list is growing and now includes other genes such as PALB2, TP53, CHEK2, and ATM. Thus, genetic testing beyond BCRA 1 and BRCA2 can yield important information for family members.

Why genetic testing matters

We know that early detection is key to a positive outcome from breast cancer. Mammography screening has shown to be invaluable for early detection. However, current guidelines do not recommend mammography screening for those under 40, a population in which breast cancer incidence rates are rising. A portion of this population may carry mutations in breast cancer susceptibility genes, and breast cancer genetic testing can make these women aware of their risk. So, it is important to understand inherited breast cancer risk factors and to know your family history to aid in your breast cancer risk assessment.

Learning if you have an inherited genetic mutation can support proactive health decisions, particularly for younger women. Your doctor may recommend earlier screening or enhanced screening with MRI or ultrasound imaging. Other preventative methods include medications or prophylactic (preventive) surgery. Your doctor can help you decide the best path for you based on the results of your genetic testing.

Genetic testing can also help doctors choose the most appropriate treatment if a person develops breast cancer. For instance, a mutation in the BRCA1 gene hinders cells’ ability to repair DNA. Researchers have found that the protein PARP (poly-ADP-ribose polymerase) aids DNA repair. PARP inhibitors were developed based on these observations: A BRCA1 mutated cell cannot repair DNA, so inhibiting a protein that can help the cell properly repair DNA would make that cell particularly vulnerable. PARP inhibitors can effectively treat BCRA1-mutated cancers, showing the value of genetic testing to inform treatment strategies. 

Who should consider genetic testing?

You should always make genetic testing decisions with your doctor, since not all women — even those with breast cancer — need it. Crucial to the process is genetic counseling before and after testing to provide context and to guide these decisions.

There are different guidelines and recommendations for genetic testing, including from the National Comprehensive Cancer Network (NCCN), the U.S. Preventive Services Task Force (USPSTF), the American Society of Breast Surgeons (ASBS), and the American Society of Clinical Oncology (ASCO). Doctors take various factors into account when recommending testing.

How genetic testing works for breast cancer

Genetic testing is a straightforward and increasingly accessible process that helps individuals understand their hereditary cancer risk. Here’s what to expect:

Genetic counseling (before testing)

Certified genetic counselors guide patients through risk evaluation and decision-making. They provide risk assessment by collecting and reviewing personal and family medical histories to:

• assess testing eligibility
• outline the benefits, risks, and limitations of genetic testing
• familiarize the patient with the process
• obtain patient consent
• discuss potential emotional impact
• and provide support

Sample collection

You will contribute a sample of saliva or blood to be processed. This can be done in a clinical setting or through home kits. Then, a lab sequences DNA from the sample and analyzes it to determine if DNA mutations in genes associated with breast cancer are present.

Results and next steps

Analysis and results usually take between 2-4 weeks. There are three different types of results:

• Positive: A mutation was found that increases cancer risk.
• Negative: No known mutation was found.
• Variant of Uncertain Significance (VUS): A gene change was found, but its effect is unclear.

Once you receive your results, your genetic counselor will consult with you to ensure you understand them and help you determine next steps.

Post-test support and planning

The amount of information that may result from genetic testing for breast cancer can be daunting. It is critical to consult with experts, such as certified genetic counselors, who can help you interpret the results and find peer or emotional support. If results are positive, your healthcare team can recommend the next steps, such as additional screening, risk-reducing medication, or preventive surgery. The findings also have implications for family members, who may also carry the mutation.

After a positive genetic test for breast cancer, there are important decisions to make that require careful consideration. It’s imperative to discuss them with professionals who can guide you. Ongoing dialogue with healthcare providers or other professionals can help clarify the results, keep you on the right path to manage your breast cancer risk, and inform family members of their possible risk.

If the results are negative or reveal a VUS, your healthcare team can help clarify what risk may still remain and advise on the best screening strategy going forward. Since active research into VUS continues, the findings may be revisited over time as their effect on breast cancer risk becomes clearer.  

Pros and cons of genetic testing for breast cancer

Genetic testing helps identify inherited gene mutations that increase cancer risk. It provides information that can guide medical care and screening, but it does not predict with certainty whether someone will develop cancer.

Overall, understanding genetic risk empowers you and other family members to take proactive steps in managing your health. In consultation with a healthcare team/certified genetic counselor, the results can help guide personalized risk-reduction strategies and inform screening and prevention plans. If you’ve been diagnosed, they can inform treatment strategies or guide participation in clinical trials.

On the other hand, contemplating genetic testing and the possible results may cause emotional stress, anxiety, or even confusion as not all gene mutations are fully understood. These are all points to consider before going forward. You can speak with your healthcare provider or a certified genetic counselor at any time — they are there to answer questions and explore what different test outcomes mean — so, ask a lot of questions. You can also find additional resources at BCRF.org.

BCRF research into breast cancer genetics and testing

BCRF researchers have long been involved in understanding breast cancer susceptibility genes. In fact, our researchers discovered BRCA1 and BRCA2, the two most well-known of these genes. These discoveries ushered in an era of advancements in breast cancer genetics and improved testing.

Today, BCRF supports cutting-edge research investigating over a dozen other breast cancer susceptibility genes as well as their prevalence in specific populations including Ashkenazim, Palestinians, and others. Other researchers, particularly those leading the CARRIERs study, are examining VUS and the role they may play in inherited breast cancer risk. Coupled with BCRF’s research in prevention, diagnosis, and treatment, genetic testing for breast cancer can be a powerful tool to swiftly move the field of personalized breast cancer care forward.

FAQs About Breast Cancer Genetic Testing

1.             How accurate is genetic testing for breast cancer?

Genetic testing for breast cancer is highly accurate when conducted in certified clinical laboratories. Tests targeting well-established mutations — such as those in BRCA1 and BRCA2 genes — have a detection rate exceeding 99 percent. However, a negative result does not eliminate all risk, as many genetic and non-genetic factors can influence breast cancer development.

Some test results may identify a Variant of Uncertain Significance (VUS) — a gene change whose impact is not yet fully understood. This underscores the importance of discussing results with a certified genetic counselor, who can help interpret findings and guide next steps. While no test is flawless, clinical-grade genetic testing remains a reliable tool for assessing inherited risk and informing medical care.

2.             What should I do if the test shows a mutation?

If testing detects a gene mutation linked to breast cancer, that means your risk is elevated but does not indicate that you will develop cancer. After receiving your results, consult a genetic counselor or oncology specialist to explore personalized risk-reduction strategies. It’s also important to seek emotional support. Many organizations, including BCRF, offer education, guidance, and community resources to help you navigate this experience.

3.             Does insurance cover genetic testing?

In many cases, yes. Insurance may cover genetic testing if you meet certain personal or family history criteria, medical guidelines, and the test is recommended by a healthcare provider. Coverage varies by health plan, so it’s important to contact your insurance provider to understand your benefits.