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BRCA1 and 2: What are they and why are we talking about them?

Disclaimer: Please note, I am not a medical professional and this article is not meant to provide medical advice. It is important to speak to a primary care provider about any concerns you have about your risk of breast and other types of cancer.

Introduction


BRCA1 and BRCA2, you may have heard these letters thrown around in discussions about breast cancer and some other types of cancer. What do these letters actually mean? Should you be worried about them? In this article, we will discuss the basics of the BRCA1 and BRCA2 genes as they relate to breast cancer, as well as what you can do if breast cancer is common in your family and you are worried about your risk of developing it too.


What are BRCA1 and BRCA2?


BRCA1 and BRCA2 stand for ‘Breast Cancer gene 1’ and ‘Breast Cancer gene 2’ (1). These are two genes that are found in our DNA. Our DNA is the genetic material in our body. Each gene is a small portion of our DNA. A gene is like a set of instructions which tells our body to produce certain proteins and perform (or not perform) certain functions (3). Cancer occurs when cells grow uncontrollably (2). The BRCA genes are both tumor suppressor genes, meaning their normal function is to help protect us from developing certain types of cancer (2). They do this by preventing cells from growing and multiplying in an uncontrolled way like cancer cells do (2).


How do the BRCA genes affect your risk of developing certain cancers?


Our genes can be mutated which means there is a change in our DNA (4). Mutations are like spelling mistakes in the DNA code that makes up a gene. In the same way that a spelling mistake can change the meaning of a word or create a word with no meaning at all, a mutation can change the function of a gene or can create a gene that is not functional at all (4).

As a result, mutations can affect the structure or function of cells in the body (4). The BRCA genes can be mutated, which prevents them from functioning normally (1). People with a mutation in either gene are at a much higher risk of developing certain types of cancers, primarily breast and ovarian cancer (5, 6). In addition, folks with a mutation in either of these genes are at a higher risk of developing these cancers at a younger age (than folks without the mutation) (6).


While cancer cannot be passed down from a biological parent to their children, some types of mutations can be (7). This includes mutations that increase a person’s risk of developing cancer, like the BRCA gene mutations (1). Cancers caused by these types of inheritable mutations are called hereditary cancer (7). In these cases, cancer may appear to run in a family, with multiple family members having the same types of cancer (7). BRCA gene mutations can be inherited in this way (1). In families with a hereditary BRCA gene mutation, there are probably multiple family members affected by breast or ovarian cancers, and often at a younger age (before the age of 50)(1).


Luckily, inheritable mutations in the BRCA genes are rare, affecting only 1 in 500 people (6). It is important to remember that having a mutation in one of your BRCA genes does not mean you have cancer and it does not guarantee that you will develop breast or ovarian cancer either (1). Cancer is complex and your risk of developing it is determined by many things aside from genetics. You can develop breast or ovarian cancer without having a mutated BRCA gene at all (1). In fact, most cancers are not hereditary, occurring instead due to environmental exposures, lifestyle factors, or by chance (3).


How do you find out if you have a BRCA gene mutation?


Your personal medical history and your family’s history of cancer may provide clues about your risk of having a BRCA gene mutation (3,8). If you are suspected to have a BRCA gene mutation, then genetic testing is required to say for sure if a mutation is present (9). Genetic testing is a type of laboratory test where a sample of your DNA is collected, usually from a sample of blood (9). The DNA is then read to search for any mutations in a gene of interest, for example in the BRCA1 or BRCA2 genes (9).


To get a genetic test, you need an appointment with a genetic counselor. A genetic counsellor is a healthcare provider who can help to assess and explain your risk of genetic conditions and the impact of a genetic condition on you and your family (3). The Canadian Association of Genetic Counsellors (CAGC) has a searchable database of genetic counsellors in Canada where you can find more information about the genetic counselling services in your area. Most of these services will require you to be referred to the counselling service by your primary care provider (3). BRCA gene mutations are rare and there are limited resources for genetic testing in Canada (6). For this reason, genetic testing and genetic counselling services are only recommended for folks who are likely to have the BRCA mutation based on their personal and family’s medical history (3).


A genetic counsellor will first ask about your family and personal health history to better assess your risk of hereditary cancers, including those related to the BRCA genes (3). Based on your risk, your genetic counsellor may recommend or advise against genetic testing (9). Genetic testing is covered by provincial health insurance (eg. OHIP) in folks who meet certain eligibility criteria that indicate they are at high risk of having a BRCA mutation (3). Your genetic counsellor can help determine whether you meet these criteria. In folks who are considered lower risk and not eligible for provincial funding, your genetic counselor may also be able to recommend private-pay options that are clinically trusted and reputable (3). Unfortunately, these services will likely require you to pay out-of-pocket. You may have heard about a number of third-party ancestry and genetic analysis websites that claim to analyze DNA. These types of services are not held to the same standard as clinical genetic testing services so they should not be used for health care management or decision-making (3).


If a genetic test is conducted, your genetic counselor will also help to interpret the results of the testing (3). They can help you to understand what your results mean for you and your family’s health, and they can help connect you to other health care professionals if necessary (3).


What can you do now?


If you are worried about having a BRCA gene mutation, or another mutation related to breast and ovarian cancer, it is important to speak with your primary care provider. It is helpful if you gather your family’s health history and share it with your primary care provider (1). Some important information to gather include any incidences of cancer in your first-degree relatives (parent, siblings, or children), as well as second-degree relatives (grandparents, aunts or uncles, nieces or nephews). When gathering this information, make sure to take note of the type of cancer the relative was diagnosed with, as well as the relative’s age at diagnosis. These pieces of information can help your primary care provider assess your risk of hereditary breast cancers like those caused by the BRCA gene mutations (3,8). Together you can determine the next steps in accessing genetic counselling services if appropriate (1).


Conclusion


While the BRCA1 and 2 genes are widely talked about, it is important to put them in perspective. Most breast and ovarian cancers are not caused by BRCA gene mutations, and having a BRCA mutation does not mean that you will develop either type of cancer. However, having a BRCA gene mutation does increase your risk of developing breast and ovarian cancer so it is important to talk to your family doctor about your risk if you have a family history (1). Being aware of your family’s medical history and your own can help ensure you and your primary care provider are well informed on your risk of hereditary cancers. Genetics can be complicated, but together with your medical team you can better understand what your genes mean for your health moving forward.



References

  1. Centers for Disease Control and Prevention. The BRCA1 and BRCA2 Genes. 2020 Mar 25. Available from: https://www.cdc.gov/genomics/disease/breast_ovarian_cancer/genes_hboc.htm [Accessed 2023 June 08]

  2. Casaubon JT, Kashyap S, Regan JP. BRCA1 and BRCA2 Mutations. 2022 September 19. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470239/ [Accessed 2023 June 08]

  3. Mount Sinai Hospital. Genetic Services for Breast Cancer. Available from: https://www.mountsinai.on.ca/care/cancer/cancers-we-treat/marvelle-koffler-breast-centre/genetics [Accessed 2023 June 08]

  4. Cleveland Clinic. Genetic Mutations in Humans. 2022 May 24. Available from: https://my.clevelandclinic.org/health/body/23095-genetic-mutations-in-humans [Accessed 2023 July 21]

  5. National Cancer Institute. BRCA Gene Mutations: Cancer Risk and Genetic Testing. 2020 Nov 19. Available from: https://www.cancer.gov/about-cancer/causes-prevention/genetics/brca-fact-sheet [Accessed 2023 June 08]

  6. Canadian Cancer Society. Risks for breast cancer. Available from: https://cancer.ca/en/cancer-information/cancer-types/breast/risks#ci_family_history_of_breast_and_other_cancers_10_185_03 [Accessed 2023 June 08]

  7. National Cancer Institute. The genetics of cancer. 2022 August 17. Available from: https://www.cancer.gov/about-cancer/causes-prevention/genetics#is-cancer-hereditary [Accessed 2023 July 21]

  8. BC Cancer Agency. Understanding Hereditary Breast & Ovarian Cancer – the BRCA genes. 2014 August. Available from: http://www.bccancer.bc.ca/coping-and-support-site/Documents/Hereditary%20Cancer%20Program/HCP_GuidelinesManuals-UnderstandingHBOCBooklet.pdf

  9. Canadian Cancer Society. Genetic Testing. Available from: https://cancer.ca/en/cancer-information/what-is-cancer/genes-and-cancer/genetic-testing [Accessed 2023 June 08]











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