The BRCA genes are the most important genes people can look for during genetic testing, when they’re looking for their genetic risk of developing serious hereditary cancers such as breast cancer, ovarian cancer, pancreatic cancer and risk of prostate cancer in male individuals. After all, a DNA test can help you figure out your genetic risk factors for various health conditions, diseases, and hereditary cancers.
Our DNA doesn’t just inform us about genetic mutations we carry in the BRCA genes (the breast cancer associated genes). Examining our DNA through a DNA test can provide us with health insights into everything from dietary issues and potential food intolerances to genetic fitness guidelines and information about our genetic body composition.
We can inherit various qualities and genetic traits from our parents, as well as genetic mutations.
An inherited mutation in the BRCA genes is frequently associated with a higher risk of breast cancer, as well as other cancers, such as pancreatic, prostate and ovarian cancer. Finding out if you have the BRCA gene mutations early could be the key to cancer prevention.
What are BRCA genes?
The term “BRCA” is actually an abbreviation of “BReast CAncer gene”. This is because two genes, BRCA1 and BRCA2 are commonly considered to impact a person’s chances of getting breast cancer. However, the BRCA genes don’t actually cause cancer on its own, despite the name.
Every human being has both the BRCA1 and BRCA2 genes. These genes are responsible for preventing cancer in most people, as they help to repair damage to the DNA which can lead to the uncontrolled growth of cells and tumors. In many cases, BRCA genes are even referred to as “tumor suppressor genes”.
The risks associated with the BRCA genes are linked to pathogenic mutations which prevent the genes from working correctly. If you inherit a mutated variation of the BRCA gene, you’ll have a higher risk of breast cancer, because the genes won’t be working correctly to prevent DNA damage.
Notably, mutations in the BRCA1 and BRCA2 genes are inherited in an autosomal dominant pattern, which means one copy of the defective gene is sufficient to increase the risk of developing breast cancer.
People who do inherit cancer-causing variations of these genes are more likely to suffer from issues with cell development, and may experience cancer at a younger age than most.
How Do BRCA Genes Influence Breast Cancer Risk?
The BRCA genes are necessary for protecting your body against various forms of cancerous growths. When cells don’t have access to fully functioning BRCA1 and BRCA2 genes, proteins in the body can grow out of control, and could potentially turn into cancer.
Research into how the BRCA gene influences cancer development is still ongoing. On average, around 13% of women in the general population are expected to develop breast cancer at some point in their lives in the US. However, 55-72% of women with a harmful BRCA1 variant, and 45-69% of women with a harmful BRCA2 gene may develop breast cancer by 70-80 years of age.
The risk level for each variant carrier will depend on numerous factors, including lifestyle, diet, and other contributing components. People with mutated BRCA genes may also be more likely to develop ovarian cancer. While only 1.2% of women in the general population are expected to develop cancer in their lifetime in the US, up to 44% of those with a harmful BRCA1 gene, and 17% of those with a harmful BRCA2 gene will be diagnosed with this cancer by 70-80 years of age.
Notably, women with a mutation in their BRCA1 or BRCA2 gene may develop recurrent breast cancer or several cancers such as breast and ovarian cancer. Those who had radiation cancer therapy to the chest or breasts before age 30 have a higher risk of developing breast cancer.
What is the Difference between BRCA1 and BRCA2 genes?
Both the BRCA1 and BRCA2 genes are connected with a higher risk of breast cancer and other cancers. However, they’re also two entirely different genes. The BRCA1 gene was first identified by medical professionals in 1990 on chromosome 17, while the BRCA2 gene is on chromosome 13.
The cancer risks associated with each gene are slightly different. For instance, BRCA1 mutation is more likely to cause an increased risk of breast cancer, ovarian cancer, pancreatic cancer and prostate cancer. Alternatively, BRCA2 genes have been connected with breast, ovarian, prostate, pancreatic, as well as melanomas.
Furthermore, cancers related to BRCA1 mutations have a higher chance of being “triple negative”, making them harder to detect, and treat than some cancers.
How Can You Be Tested for the BRCA Genes?
Examining your genetic background with DNA testing is an excellent way to learn more about your risks. DNA tests can check for mutations in the BRCA1 and BRCA2 gene. Medical professionals can also provide genetic profiling to help fully understand the risk of each individual.
Usually, before a test is carried out, people will undergo a risk assessment with their doctor, which involves meeting with a genetic counselor to review factors which increase their risk of cancer. For instance, those with close relatives who also had cancer may be at higher risk. If the assessment suggests a person may have an increased risk of a BRCA gene mutation, a test will be carried out using saliva, or blood.
It’s also possible to check for your risk of a mutated BRCA1/2 gene variant using at-home DNA testing kits, which can provide you with an insight into your risk, so you can further discuss your options with your doctor. This form of testing can be particularly convenient for someone who believes they may have a higher risk of cancer, due to their family history.
Since cancer-causing mutations are typically inherited from the mother or father, family history is usually the best indication of whether a mutation might be present. The following warning signs may indicate you have a higher chance of a BRCA1/2 variant:
- Two or more first or second degree relatives with breast cancer, if at least one breast cancer was diagnosed before age 50
- One or more first or second degree relative(s) with an early diagnosis of breast cancer (younger than 45)
- Three or more first or second degree relatives with breast cancer at any age
- One or more first or second degree relative(s) with a cancer diagnosis attributed to both breasts
- Breast cancer development in one or more first or second male relative(s)
- Any first or second-degree relative with both breast and ovarian cancer
- One or more first or second degree relative(s) with triple negative breast cancer diagnosed at age 60 or younger
Certain ethnic groups also have a higher risk of these mutations, including Scandinavian people, and individuals with Ashkenazi Jewish backgrounds. People of Ashkenazi Jewish descent have a 1 in 40 chance of developing a harmful mutation of BRCA1 or BRCA2.
Why is Genetic Testing for the BRCA Gene Important?
The discovery of a mutation in a BRCA gene during a DNA test doesn’t guarantee breast cancer will develop. However, it does indicate you may have a higher risk of breast cancer than others, and an increased chance of a more aggressive form of tumor.
Genetic testing at an early age will help you to take a proactive approach to your treatment. For instance, your doctor might recommend:
Early screening: If you test positive for mutated BRCA genes, you may start breast cancer screening at a younger age (as young as 30 years old), and engage in screening mammograms more often than others (such as annually instead of every 2-3 years). This will help improve your chances of catching breast cancer early, and early detection makes all the difference in survival.
Risk-reducing surgery: Prophylactic mastectomy involves removing as much of the tissue at risk of breast cancer as possible. Both breasts can be voluntarily removed to reduce your risk of breast cancer in extreme cases.
Chemoprevention: Certain medications can be used to reduce a person’s breast cancer’s risk. The use of certain drugs for breast cancer risk reduction in people with mutated BRCA genes hasn’t been fully tested yet. However, studies show it could be useful.
Whether you receive a positive or negative result, there can be numerous benefits of genetic testing. A negative result can be a source of relief for people who have a family history of breast cancer. Alternatively, a positive result makes it easier to make decisions about how to tackle your treatment at the earliest with better prognosis.
The Implications of a BRCA Mutation
The BRCA1 and BRCA2 genes are involved in the process of gene repair. This means people with these variations might struggle more with their treatment than others. There is a class of drugs known as PARP inhibitors which can help to reduce the growth of cancerous cells with harmful BRCA gene variants, and your doctor can adjust your treatment to suit your genetic profile.
While a mutation in the BRCA genes can indicate a higher risk of breast cancer, it’s still possible to recover from breast cancer with these genes. The best strategy is to use genetic testing to find the potential issue quickly, so you and your doctor can arrange a prevention plan for you.
Knowing if you have one of these genetic variants could also mean you can provide future generations of your family with genetic insights, so they can be tested at an earlier age.
References:
- Hereditary Breast Cancer and BRCA Genes: https://www.cdc.gov/cancer/breast/young_women/bringyourbrave/hereditary_breast_cancer/index.htm#:~:text=BRCA1 and BRCA2 are two,or in an uncontrolled way.
- Risks of Breast, Ovarian, and Contralateral Breast Cancer for BRCA1 and BRCA2 Mutation Carriers https://pubmed.ncbi.nlm.nih.gov/28632866/
- SEER Cancer Statistics Review (CSR) 1975-2017 Released April 15, 2020 https://seer.cancer.gov/archive/csr/1975_2017/
- Meta-analysis of BRCA1 and BRCA2 penetrance https://pubmed.ncbi.nlm.nih.gov/17416853/
- The BRCA1 and BRCA2 Genes | CDC https://www.cdc.gov/genomics/disease/breast_ovarian_cancer/genes_hboc.htm
- Jewish Women and BRCA Gene Mutations | Bring Your Brave | CDC https://www.cdc.gov/cancer/breast/young_women/bringyourbrave/hereditary_breast_cancer/jewish_women_brca.htm
- Tamoxifen and breast cancer incidence among women with inherited mutations in BRCA1 and BRCA2: National Surgical Adjuvant Breast and Bowel Project (NSABP-P1) Breast Cancer Prevention Trial https://pubmed.ncbi.nlm.nih.gov/11710890/
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