Genetic Testing for Breast Cancer

Breast cancer is the second most commonly diagnosed cancer of women in the United States, after skin cancer. Men, too, can get breast cancer, although it is predominantly a woman’s disease.

The disease is caused by cells in the breast that begin to divide much more rapidly than normal. They form a mass that can then spread through the lymph nodes to other parts of the body.

Advances in the treatment of breast cancer in recent years have resulted in increased survival rates. Earlier detection is one important factor that has improved the odds of survival.

Genetic testing for breast cancer

There are many factors that may increase your risk of breast cancer including lifestyle and environmental and hormonal factors. However, doctors estimate that 5% to 10% of breast cancers are caused by inherited gene variants, or mutations. The risk of these types of cancers can be assessed through genetic testing.

Specifically, genetic testing can look for evidence in your genome of the gene variants known as Breast Cancer 1 (BRCA1) and Breast Cancer 2 (BRCA2). If these variants are present, you are said to have Hereditary Breast and Ovarian Cancer (HBOC) syndrome.

Men can also inherit BRCA variants. For men, the presence of these variants can mean an increased risk of breast cancer, high-grade prostate cancer, and pancreatic cancer.

If you find that BRCA1 and/or BRCA2 are present in your DNA, that doesn’t necessarily mean you will get breast cancer. You can take preventative measures to decrease the risk of suffering from breast cancer and other types of cancers.

Who should be screened for hereditary breast cancer?

Many expert groups have developed guidelines for genetic testing for breast cancer. These guidelines identify who should seek genetic counseling and testing for BRCA gene variants. However, these guidelines aren’t globally agreed upon. They are simply considerations when it comes to breast cancer and genetic testing.

According to the guidelines, you should seek genetic testing for breast cancer if any of the following are true:

You were diagnosed with breast cancer before and are in remission. If you are a triple-negative breast cancer survivor, you should highly consider seeking genetic testing.
You have suffered from breast cancer more than once but have not had a recurrence of the first breast cancer diagnosis.
You are of Ashkenazi Jewish or Eastern European descent.
You have a family history of one of the following cancers: breast, ovarian, pancreatic, or prostate.
You have a family history of BRCA variants.
You have a family history of breast cancer at a young age or more than one family member (male or female) who has suffered from breast cancer.
You have close family members who have a history of ovarian cancer, pancreatic cancer, or metastatic prostate cancer.

While these guidelines focus on those who have suffered from breast cancer or who have a family history of it, people of all ages should consider getting genetic testing, even children and babies. If a genetic breast cancer predisposition is discovered in a child, preventative measures—such as avoiding chest x-rays when that child has a cough—can be followed. They are most effective when started early and continued throughout life.

Are there other gene variants that can lead to breast cancer?

BRCA1 and BRCA2 gene variants have received a lot of media attention because they were the first variants identified as contributing to an increased risk of breast cancer and/or ovarian cancer. However, there are actually many different genetic variants in a large number of other genes that are also associated with an increased risk of breast cancer. Accurate analysis of risk should take them all into consideration.

One of the gene variants that also appears to be indicative of a risk for breast cancer is the Partner and Locator of BRCA2 (PALB2). This gene instructs the body to make a protein that works with BRCA2 protein to repair DNA that is damaged. When PALB2 is not working properly, cells become abnormal, leading to tumor growth.

Genetic testing for PALB2 began after 2013, so if you were genetically tested for breast cancer before that time, you should consider testing again for PALB2.

Where to get genetic testing for breast cancer

Sequencing.com’s Marketplace offers a DNA analysis app called Prevent Breast Cancer. It will provide you with a comprehensive analysis of your BRCA1, BRCA2, and PALB2 genes, as well as many other genes that are important for determining your genetic risk of breast cancer and ovarian cancer.

The Prevent Breast Cancer app can analyze DNA data from almost any genetic test, such as genotyping or microarray genetic testing used by third-party providers like 23andMe, MyHeritage, and AncestryDNA.

Sequencing.com also offers whole genome sequencing which sequences your whole genome—all 30,000 genes, including BRCA1, BRCA2, and PALB2.

The whole genome sequencing test kit can be mailed directly to your home. The test requires a simple cheek swab that you then mail to the lab. Depending on the turnaround time you select, you can have your sequencing results in as little as three weeks.

Once your whole genome is sequenced, you can use the data to run reports on a host of health, wellness, and ancestry topics, including breast cancer risk.

Whether you use DNA data from a third party vendor or from Sequencing.com’s whole genome sequencing, the Prevent Breast Cancer app will analyze your DNA for the following 10 genes associated with breast and/or ovarian cancer:

BRCA1
BRCA2
PALB2
BARD1
ATM
CHEK2
PTEN
TP53
FGFR2
TNRC9

The report will then provide you with insights about:

Your genetic risk of breast cancer.
Your genetic risk of breast cancer with radiation exposure (such as from chest x-rays, CAT scans, and mammograms).
Your genetic risk of ovarian cancer.

What can I do if I find out I have a genetic risk of cancer?

Sequencing.com seeks to help you prevent breast cancer by offering multiple comprehensive analysis apps, including the Prevent Breast Cancer app. These apps will alert you to gene mutations typically found in people who have been diagnosed with breast cancer.

With the findings from Sequencing.com’s breast cancer suite of apps, you can work with a genetics counselor or your health care professional to lower the risk of suffering from breast cancer.

Ongoing research on breast cancer

Many research studies and clinical trials are exploring the causes of breast cancer, as well as new and better ways to treat it. While some genetic variants, or mutations, connected to an increased risk of breast cancer have been identified, there are currently studies dedicated to discovering even more.

In addition, researchers are also exploring:

The best uses of genetic testing to identify inherited gene variants that lead to breast cancer.
How common gene variants that pose little risk of cancer by themselves could combine to have a bigger impact.
The possible impact of environmental factors on the risk of breast cancer.

One of the most promising avenues of treatment research is the use of biomarkers to help personalize treatments for breast cancers. Biomarkers are genes, proteins, or other substances that can be found in biological material like blood and tissues.

In the case of cancer, when cancer cells die they release circulating tumor DNA (ctDNA). Researchers are working on techniques for identifying ctDNA and testing it. They may be able to use biomarker information obtained from ctDNA to help in the fight against cancer, including:

Determining if a certain drug will work on a given tumor before administering it.
Identifying if a cancer has become resistant to a certain treatment, such as chemotherapy.
Predicting if an early stage cancer has a high chance of recurring.

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About the Author

Dr. Brandon Colby MD is a US physician specializing in the personalized prevention of disease through the use of genomic technologies. He’s an expert in genetic testing, genetic analysis, and precision medicine. Dr. Colby is also the Founder of Sequencing.com and the author of Outsmart Your Genes.

Dr. Colby holds an MD from the Mount Sinai School of Medicine, an MBA from Stanford University’s Graduate School of Business, and a degree in Genetics with Honors from the University of Michigan. He is an Affiliate Specialist of the American College of Medical Genetics and Genomics (⁠ACMG), an Associate of the American College of Preventive Medicine (⁠ACPM), and a member of the National Society of Genetic Counselors (⁠NSGC).