Breast cancer affects thousands of people every year. It’s one of the most common cancers faced by women: about 13% of women will develop breast cancer at some point in their lives.
One of the most common questions about breast cancer is, “Is breast cancer hereditary?” And the answer is yes, it can be.
Understanding your risk of developing hereditary breast cancer can help you get the screenings and preventive care you need. In this post, we’ll talk about the different types of hereditary breast cancer, genetic testing for breast cancer risk through genetic counselors and community health research studies like myGenetics, and what to do if your test reveals you may have a genetic mutation that increases your risk of developing a disease.
Hereditary breast cancer is inherited through DNA
Hereditary breast cancer is caused by genetic mutations passed down from your parents. Five to 10% of breast cancer cases are caused by inherited gene mutations.
Genes are made up of DNA, and some changes within the DNA (also referred to as mutations) are linked to an increased risk of breast cancer. BRCA1 and BRCA2 are the most common genes linked to breast cancer, and we’ll talk more about them. But inherited mutations in other genes can also impact your risk of developing breast cancer.
While having a history of breast cancer in your family might mean you have a genetic mutation that increases your risk, the only way to know for sure is through genetic testing for gene mutations associated with breast cancer risk.
Keep in mind that having a gene mutation that increases your risk of breast cancer doesn’t mean you’ll develop the disease. There are preventive measures that can be taken to reduce your risk, including earlier and increased imaging, preventive surgical options, and preventive medications.
What is familial breast cancer and how does it affect your risk?
Breast cancer sometimes occurs more frequently in families for reasons other than an inherited single gene mutation. About 10-20% of breast cancers may be caused by a combination of genetic, environmental and lifestyle risk factors that family members have in common. This is called familial breast cancer, and breast cancer risk among family members may be more difficult to predict.
Studies show that a family history of breast cancer increases your risk of developing the condition during your lifetime. If one of your first-degree female relatives – mother, sister or daughter – has breast cancer, your personal risk of breast cancer doubles. Your risk of developing breast cancer is significantly higher than average if two of your first-degree relatives are diagnosed with breast cancer.
Just like with hereditary breast cancer, family history of the disease doesn’t mean you’ll be diagnosed with breast cancer for certain. But there are different steps you can take to reduce the risk of breast cancer, depending on your family history. Talk with your primary care doctor if you have concerns about your family’s cancer history, and consider asking about a referral to a breast health expert for a more personalized risk assessment.
Genetic testing for hereditary breast cancer risk looks for mutations in the BRCA1 and BRCA2 genes
The BRCA1 and BRCA2 genes are associated with several different types of cancer, including breast cancer. When working properly, BRCA1 and BRCA2 act as tumor suppressors and help protect your body from cancer.
However, it’s possible to inherit BRCA1 and BRCA2 mutations that keep the genes from doing their jobs. These mutations are associated with a higher risk of breast cancer and ovarian cancer in women, prostate cancer in men, and pancreatic cancer and melanoma in both sexes.
The lifetime risk of cancer for a woman who carries a BRCA mutation is more than 60% compared to the general population risk of 13%.
You can inherit a BRCA mutation from either parent
About 1 in 500 women in the United States have either a BRCA1 or BRCA2 mutation. Most people inherit these gene mutations from one of their parents. It is also possible for someone to be the first person in their family to carry a new mutation, but this is rare.
It’s possible to inherit mutations on the BRCA1 or BRCA2 gene from either parent. If your mother or father has a mutation, you have a 50% chance of having the same mutation.
Who should get genetic testing for hereditary breast cancer risk?
There are some groups of people who are more likely to carry BRCA1 and BRCA2 gene mutations. Understanding your breast cancer risk can help you take proactive steps, like increased screening and preventive care.
Genetic testing for hereditary breast cancer risk may be a good fit for people who:
- Have several family members who have had breast cancer
- Have male family members with breast cancer
- Have a family history of ovarian cancer
- Have a relative with a known BRCA mutation (or other gene mutation)
- Have a relative who was diagnosed with breast cancer earlier than age 50
- Have a personal history of breast cancer before age 50, male breast cancer or triple negative breast cancer (a type of breast cancer with cells that don’t have estrogen receptors, progesterone receptors or the HER2 protein)
- Have a personal history of ovarian cancer, fallopian tube cancer or primary peritoneal cancer
Your ethnicity also has an impact on the likelihood that you have a BRCA mutation. People of Ashkenazi Jewish descent are far more likely to have a mutation in the BRCA1 or BRCA2 gene. One in 40 Ashkenazi Jewish women have a mutation, compared to the average risk of 1 in 500.
Because hereditary breast cancer is passed through relatives, you may also carry the abnormal gene if someone in your family tests positive for a BRCA gene mutation. If you have a family member with a known mutation in a breast cancer risk gene, it's recommended that you meet with a genetic counselor to discuss what these results mean for you, as well as to discuss your options for genetic testing.
Undergoing genetic testing for hereditary breast cancer is a personal decision. If you’re unsure about breast cancer genetic testing, you should talk with your doctor. They can help answer your questions, determine if testing is needed, and guide you toward the path that will be best for you.
How genetic testing for hereditary cancer works
Genetic counseling and testing are recommended for those whose family and personal health histories point to an increased chance of a cancer gene mutation. In many cases, testing someone in the family with a cancer diagnosis will provide the most information. Sometimes this isn’t possible because the family member has passed away or declined genetic testing. In this scenario, their close relatives may choose to pursue testing.
Comprehensive genetic testing for hereditary breast cancer risk typically involves a multi-gene panel that can analyze several breast cancer susceptibility genes at the same time. We know that inherited BRCA1 and BRCA2 gene mutations carry significantly higher lifetime risks for breast cancer and are responsible for a large portion of hereditary breast cancer families.
There are two main options for accessing genetic testing: meeting with a genetic counselor and genetic testing health research studies.
Genetic counseling
A genetic counselor is trained to talk about inherited genetic disorders. They can analyze your personal and family medical history, provide risk assessment and help you consider your testing options. They can also talk with you about what a genetic test result means for you and your family.
If needed, genetic counselors can guide you toward additional care that might help you manage your health risks. If you have a personal or family history of cancer, talk with your primary care doctor about whether a visit with a genetic counselor is right for you.
DNA health studies and screening programs sometimes offer breast cancer genetic testing and other types of genetic health tests. In Minnesota, myGenetics is a first of its kind large-scale community health research study. This voluntary study is available to all HealthPartners and Park Nicollet patients over the age of 18 that do not have a history of a bone marrow or stem cell transplant from a donor.
Through myGenetics, you can get information about three hereditary conditions: Lynch syndrome, hereditary breast and ovarian cancer, and a hereditary form of high cholesterol called familial hypercholesterolemia. You can also get information on regional ancestry and traits like caffeine sensitivity. All this information from myGenetics is available at no cost to you.
Learn more about genetic testing with myGenetics DNA health screening.
What to do if you test positive for a genetic risk of hereditary breast cancer
Keep in mind that an increased risk of breast cancer doesn’t mean that you will develop it, but it’s still important to be aware of your personal risk. Having a hereditary or familial risk of developing breast cancer affects the preventive care and screenings you need. Lifestyle changes, increased screening through imaging, preventive surgeries and certain medicines are all methods that can be used to reduce your risk of developing cancer.
High-risk evaluation and screening
If you have a genetic predisposition to developing breast cancer, your care team will work with you to create a regular screening plan. Depending on your personal risk, you might get screenings for breast cancer every six months. This increases the likelihood things will be detected early.
People at risk of hereditary breast cancer or with a family history of the disease commonly start breast cancer screenings at an earlier age than is typically recommended. In some cases, your doctor may recommend starting breast cancer screenings 10 years before the earliest breast cancer diagnosis in your family. For example, if your mother was diagnosed at age 40, you might start breast cancer screenings at 30.
Medications to reduce breast cancer risk
Certain medications can be an effective way to reduce the risk of developing breast cancer in people at higher risk. Some types of medicine that may be used include:
- Tamoxifen and raloxifene – These are both FDA-approved medications for reducing the risk of breast cancer. Tamoxifen can be used by women at any stage of life, while raloxifene is only for post-menopausal women.
- Aromatase inhibitors – Research shows that aromatase inhibitors can decrease the risk of developing breast cancer and may be an effective option for you.
Make sure to talk with your doctor before starting any new treatment. Like with many types of care, medication therapy comes with a risk of developing side effects. Your doctor will help you weigh the risks and benefits of these therapies considering your risk of genetic breast cancer.
Surgery
In some cases, people who carry BRCA1 or BRCA2 mutations may choose to surgically remove their breast tissue – called a double mastectomy. By removing as much breast tissue as possible, the likelihood that cancer develops is significantly lower.
A double mastectomy is a personal, life-altering choice. You should let your doctor know if you’re considering the procedure. They’ll talk with you about the benefits and risks of surgery, what to expect during recovery and your options for reconstruction.
Find out if hereditary breast cancer is a risk factor for you
If you’re interested in learning if you carry a gene mutation, genetic testing for breast cancer risk might be right for you. Talk with your primary care doctor about your options for genetic testing and whether a genetic counselor or a community health research study like myGenetics is right for you.
If you have a personal or family history of breast cancer, you can still participate in the myGenetics program, but it’s important to know that the genetic screening offered through myGenetics includes only a subset of genes that can cause an increased risk for cancer. If you have a personal or family history of cancer, you should review this information with your care provider or a genetic counselor to determine if more comprehensive testing would be appropriate for you.