Inherited gene mutations are often linked to a family cancer syndrome. Most are rare. Not everyone with a family cancer syndrome develops cancer.
Breast Cancer Genes
If you have a powerful family history of certain cancers, there might be a faulty gene in your family that increases your risk of breast cancer. We know about several gene faults that can increase breast cancer risk, and there are tests for some of them.
Genes that increase the risk of breast cancer are BRCA1 and BRCA2. BRCA stands for BReast CAncer gene. Everyone has BRCA1 and BRCA2. These genes stop cells in our body from growing and dividing out of control. If there is a fault (mutation) in these genes, it means that cells can grow out of control. This can lead to the development of several cancers, including breast cancer.
Other genes that could increase your risk of developing breast cancer if they have a fault include:
Having one of these faulty genes means that you are more likely to get breast cancer than someone who doesn’t. But it is not certain.
Remember that most breast cancers happen by chance. Researchers estimate that only around 5 to 10 out of 100 breast cancers (5 to 10%) are caused by an inherited faulty gene.
Understanding Family History
Many patients have questions about what it means to have a family history of breast or ovarian cancer. Doctors usually look only at close blood relatives – such as your mother, sisters, and daughters – when determining your family history of these diseases. If one or more of these relatives has had breast or ovarian cancer, your own risk is significantly higher.
If a grandmother, aunt, or cousin has been diagnosed with the disease, your risk is usually not significantly changed, unless many of these “second-degree relatives” have had the disease.
Breast Cancer Factors
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- Female sex. Patients who were female at birth account for more than 99% of breast cancer cases.
- Age. The older you are, the greater your chance of getting breast cancer.
- Personal or family history. Your risk is higher if you or a close relative has had breast cancer (including ductal carcinoma in situ, which is the earliest form of breast cancer) or certain benign breast conditions (such as atypical ductal hyperplasia and lobular carcinoma in situ).
- Genetic predispositions. The most common examples are mutations in the BRCA1 and BRCA2 genes. Each person has two copies of both genes, one from each parent. If you inherited a variant, you have a higher risk of getting several types of cancer, including breast and ovarian cancer. For more information, consider making an appointment with a genetic counselor.
- High lifetime estrogen exposure. Your cumulative exposure to estrogen (the hormone that plays a key role in female sexual development) may be higher if you began menstruating early (before age 11), began menopause late (after age 55), or have been on estrogen and progesterone therapy (hormone replacement therapy) for more than 10 years.
- Dense breast tissue. Breasts are made up of several types of tissue. Dense breasts have less fatty tissue and carry an increased risk of cancer. A mammogram can show your breast density.
- Radiation therapy in the chest area. Having undergone radiation therapy in the chest area (for example, to treat Hodgkin’s lymphoma) slightly increases breast cancer risk. The increase is highest if the radiation therapy occurred before age 30
- Race and ethnicity. The Centers for Disease Control and Prevention report that Caucasian and African American women have the highest incidences of breast cancer, followed by Asian and Hispanic women. Caucasian individuals are most likely to be diagnosed with breast cancer, but African American individuals are more likely to die from the disease.
Limit Hormone Replacement Therapy (HRT): Some types of HRT can increase your chance of developing breast cancer, though the significance of the risk varies depending on several factors, including how long you use it and the dose you take. And for many women, the risks outweigh the benefits. If you have a family history of breast cancer and you’re concerned about using HRT, talk to your doctor about whether it’s safe for you.
Increased Screening: Women found to be at high risk of breast cancer due to a strong family history of the disease and/or a genetic mutation may need more frequent screening than those with no family history or mutations. Your doctor will develop a personalized screening plan for your situation, which may include annual mammograms. Supplemental screening, such as MRI or whole-breast ultrasound (WBUS), may also be recommended because they provide more detailed images of breast tissue.
You might also need to start screening early. Most major health organizations recommend getting your first mammogram at age 40, but if you’re at high risk of breast cancer, you may benefit from starting to screen at age 30 or younger.
Medication: Preventive therapy, or chemoprevention, is an option for those at substantial risk of breast cancer in addition to recommended screening. There are two types of risk-reducing medication, which work by blocking estrogen in the body:
Selective estrogen receptor modulators (SERMs). The SERMs tamoxifen and raloxifene can cut the risk of breast cancer by about 40 percent. They work by blocking estrogen, which can fuel the growth of breast cancer cells. Both drugs are FDA-approved to reduce the risk of breast cancer in women with higher-than-average risk. However, raloxifene is only approved for postmenopausal women, while tamoxifen is approved for both pre- and postmenopausal women. SERMs may not be recommended if you have a history of blood clots.
Aromatase inhibitors (AIs): Extensive studies have shown that the AIs anastrozole and exemestane can lower the chance of developing breast cancer in some post-menopausal women who are at increased risk of the disease. While they’re not FDA-approved for this purpose, doctors do prescribe them to specific patients, such as those with a history of blood clots who shouldn’t take tamoxifen or raloxifene.
Surgery: If your risk of hereditary breast cancer is extreme, your doctor may suggest preventive surgery (or prophylactic surgery). The most common procedure used—a bilateral risk-reducing mastectomy—has been shown to cut the risk of developing the disease by 90 percent in women with a strong family history of the disease. In this procedure, your surgeon may perform a total mastectomy—meaning the nipple and areola are removed—or a nipple-sparing mastectomy, which preserves the nipple and areola. Both are highly effective, but a total mastectomy provides slightly more protection.
SUMMARY
There is no doubt that some forms of breast cancer can run in families. But just because one of your relatives had breast cancer does not mean you, too, are destined to develop it. At the same time, if you are at risk, continual monitoring and screening are essential so your doctor can catch and treat any breast cancer that may arise as early as possible.
Your children need to know about their family health history. If you or other family members have had genetic testing that found a gene mutation, your children may also choose to get tested at the appropriate time.
You may also wish to tell other family members that you are being tested and talk to them before you get the results of your test. Some family members may want to know if you have a genetic change linked to cancer so they can decide if they should also get tested. But others may not want to know your test results or find out their own risk.
https://bcrisktool.cancer.gov/index.html
Breast Cancer Risk Assessment Tool
https://bcrisktool.cancer.gov/calculator.html
References
Breast Cancer Research Foundation
Canadian Cancer Society
Cancer Research UK
National Cancer Institute
UCSF Health
