When breast cancer runs in your family genetics, it’s known as hereditary breast cancer. If a loved one has recently received this diagnosis, certain factors can provide insight into your individual risk level.
Breast cancer refers to a variety of cancers originating in breast tissue. Your individual diagnosis will depend on factors like which cells cancer affects, the characteristics of those cancer cells, and the rate at which cancer has grown and spread.
If you have a family history of breast cancer, there’s a good chance a genetic variant, passed down from parent to child, directly increases your risk of also being diagnosed with breast cancer at some point in life.
According to the American Cancer Society,
Having breast cancer in your family doesn’t guarantee you’ll develop it, but it can mean you have a higher risk compared to the broader population. Understanding your hereditary risk factors can help you develop proactive prevention and early detection strategies.
Your genetics provide the DNA (deoxyribonucleic acid) blueprints essential to your growth, development, and overall function. They’re passed down to you in two sets of chromosomes, one from each of your parents.
Certain genetic variations can be passed down from parent to child, including some related to breast cancer. Genetic variants are unusual alterations in a section of DNA that changes how a gene expresses itself. An easy way to think of it is like receiving the wrong directions for how to use an appliance.
Genetic variants that are hereditary are called “germline mutations,” because they’re present in germline cells (sperm and eggs). Some people can develop genetic alterations later in life that weren’t passed down by their parents. These are called “somatic mutations,” and some can also contribute to breast cancer development.
If a loved one has been diagnosed with a type of hereditary breast cancer, it means a germline mutation passed down from a parent directly contributed to breast cancer development.
The most common germline mutations associated with hereditary breast cancer occur in the genes BRCA1 and BRCA2. If you carry one of these variants and were assigned female at birth, you have a
Other known genetic variants that can increase your hereditary breast cancer risk include mutations in the following genes:
- ATM
- PALB2
- TP53
- PTEN
- CHEK2
- STK11
- CDH1
Does the closeness of a relative matter?
How close a relative with hereditary breast cancer is to your family tree affects your risk. This is because first-degree relatives, like your parents and full siblings, share the most genetic material with you.
You share 50% of your genetics with each parent and
The further away you get in the family tree from a relative diagnosed with breast cancer, the less genetic material you share. You only share about 25% of your genetic material with your full aunt, for example, because she only shares about 50% with one of your parents (and that 50% is split when passed on to you).
How many family members have been diagnosed with hereditary breast cancer also affects your risk level. The more relatives affected, the higher your individual chances of developing breast cancer. Having two first-degree relatives with the diagnosis increases your risk by
Your risk increases with the number of family members because the chance of shared genetic material increases, but also because there may be other family-specific inherited factors contributing to breast cancer risk (known as familial clustering).
How race and ethnicity factor in
Your genetics are also influenced by the long timeline of your ancestry. Certain breast cancers are more prevalent among specific populations. African American females, for example, are
In the United States, BRCA mutations are
While many different environmental and socioeconomic factors influence racial disparities in breast cancer, genetic differences among distinct populations are thought to play a role.
Knowing your family history
Knowing your family history of breast cancer is one of the most important components in “risk stratification,” the process of determining your personal breast cancer risk.
Doctors use your family history along with your individual medical history and lifestyle factors to place you in an average, moderate, or high risk category.
Your risk level is then used to develop a comprehensive, personalized strategy for the prevention and early detection of hereditary breast cancer.
To help your doctor with the risk stratification process, gather all the information you can about family history, including:
- which family members were diagnosed with breast cancer
- what specific type of breast cancer was diagnosed
- how old family members were when diagnosed
- the presence of any other cancers in the family
Many different healthcare professionals can help you understand your personal risk for hereditary breast cancer.
Your primary care physician (PCP) is a great person to speak with initially. They already have access to and knowledge of your personal medical history, and they can calculate your risk stratification using several different medical models, like the
When genetics are involved in breast cancer, your PCP may recommend speaking with a genetic counselor. Genetic counselors can offer more in-depth risk assessment and management strategies based on the results of genetic testing.
Your genetic counselor’s role is to help you understand your unique genetic risk factors and why certain risk reduction strategies, like earlier or more frequent screening tests, should be considered.
Bring all of your family history details, and contact your PCP office to have your personal records sent over ahead of time.
Preparing a list of questions for your genetic counselor can help your appointment move smoothly and ensure you don’t forget any important topics. It’s OK to bring a loved one along for support or to take notes for clarity.
Do you need an oncologist?
Oncologists specialize in the treatment of cancer. If you haven’t been diagnosed with breast cancer, visiting an oncologist isn’t necessary to understand your personal risk factors.
You may want to involve an oncologist, however, if you’re considering advanced preventive measures, like a prophylactic mastectomy, or if you have a prior history of cancer (of any kind) and are already on a screening schedule under their care.
Oncologists specializing in breast cancer can also provide a professional perspective into the specialized treatment and prevention of breast cancer, which a PCP or genetic counselor may not have as much in-depth experience with.
Your genetic counselor will discuss the pros and cons of genetic testing before recommending a certain type of test.
Genetic testing can provide insight into your risk factors and can help with informed decision making, but some people may find it emotionally taxing, and genetic tests don’t always produce clear results.
New genetic risk factors are still being discovered, and there may be many still unknown that can’t be screened for (yet).
If testing is recommended, you’ll need to provide a blood, saliva, or cheek (buccal) swab sample that can be sent to a laboratory for DNA analysis.
Fasting isn’t necessary for genetic testing, but depending on the type of test, you may be asked to avoid eating, drinking, smoking, or chewing gum before providing a sample.
If blood is submitted, your doctor or a nurse will draw the sample directly from your vein in an outpatient setting. You may experience some discomfort or irritation at the site of the needle insertion.
Saliva tests and swab tests may be gathered at home or in an outpatient setting, as well.
Once received by the laboratory, your sample goes through DNA extraction, which allows the identification of specific genetic sequences related to breast cancer risk.
Any discovered identified genetic variants are classified as likely harmful (pathogenic), likely harmless (benign), or as variants of uncertain significance (VUS).
Your results are sent to your genetic counselor, who will explain them in detail and discuss how they affect prevention strategies.
A high risk for breast cancer is not a guarantee of breast cancer.
Many people have multiple risk factors and never develop cancer, and some people without any risk factors go on to receive a cancer diagnosis.
If your risk stratification process indicates you’re at high risk for breast cancer, it’s natural to feel overwhelmed at first about what steps to take next. It’s OK to take your time to work through this process, and you may find it easier to make informed decisions if you do the following:
- Ask for recommendations from your pcp, genetic counselor, and other medical specialists.
- Talk with family members about their breast cancer experiences.
- Participate in support groups to learn from others in the breast cancer community.
- Research the pros and cons of available prevention strategies.
- Seek second opinions from other breast cancer specialists.
You can’t control your genetics, but other risk factors for breast cancer can be controlled. Even if breast cancer runs in your family, you can reduce your risk for breast cancer overall by:
- eating a balanced diet rich in whole foods
- reducing or eliminating alcohol consumption
- getting regular exercise
- maintaining an optimal weight
- quitting smoking, if you smoke
- following the regular
mammogram screening guidelines for your age and risk group - having an annual breast MRI (magnetic resonance imaging) if you are high risk
- limiting exposure to pollutants associated with breast cancer, like polychlorinated biphenyls (PCBs).
For a very small number of people with a higher-than-average risk for breast cancer, more advanced risk reduction options may be considered.
Chemoprevention is a proactive therapeutic approach that involves taking medications to block the action of the hormone estrogen in breast tissue, potentially lowering cancer risk. Chemoprevention isn’t for everyone, and like all medications comes with a variety of potential adverse reactions and contraindications.
Another option is preventive surgery, also known as a prophylactic mastectomy. By removing the breast tissue, it’s possible to decrease your risk for breast cancer by as much as
Genetic variants passed down from parent to child through germline mutations can increase your risk for breast cancer. These hereditary patterns are why breast cancer may run in your family, and they’re an important clue to your overall breast cancer risk.
While you can’t control your genetics, having genetic risk factors does not guarantee you’ll develop breast cancer.
You can decrease your breast cancer risk overall by focusing on beneficial lifestyle modifications, keeping up with routine cancer screening, and speaking with doctors about individualized prevention strategies.