While all women are at risk of developing breast cancer over the course of a lifetime, there are a range of factors that can increase breast cancer risk. These factors include family history and genetic susceptibility. Approximately 5-10% of breast cancer cases are thought to be hereditary, where the gene mutation has been passed on directly from a parent.
The most commonly inherited gene mutations are known as the BRCA1 or BRCA2 gene mutation. In normal cells, these genes help make proteins that repair damaged DNA. Mutated versions of these genes results in accumulation of damaged DNA which can lead to abnormal cell growth, which can then lead to cancer.
Here, experts from the upcoming Breast Cancer Trials Q&A (taking place October 24th from 5-6.30pm) – genetic cancer experts and researchers, Professor Geoff Lindeman and Professor Kelly-Anne Phillips, Dr Milita Zaleed, staff specialist in cancer genetics and Chair of NSW/ACT Familial Cancer Clinics community of practice and Ms Karen Alexander – alongside Dr Nick Zdenowski – share everything there is to know.
Are genetic breast cancers more aggressive?
Genetic breast cancers are more often diagnosed at a young age, and BRCA1-related breast cancer is more likely to be triple negative than non-genetic breast cancer. These factors are associated with a higher risk of recurrence, along with the stage of the cancer. Patient factors, the type of cancer, and stage have a greater impact on recurrence and survival than the genetic alteration itself.
Are genetic cancers the reason why young women get breast cancer?
While all women are at risk of developing breast cancer over the course of a lifetime, there are a range of factors that can increase breast cancer risk in young women. These factors include family history and genetic susceptibility. A strong history of breast cancer among relatives is an important risk factor, especially for those who have inherited a gene mutation such as BRCA1 or BRCA2.
If someone has a ‘breast cancer causing’ genetic mutation, what is the likelihood that they would pass this onto their children? And their grandchildren?
Both women and men who have inherited an abnormal breast cancer gene have a 50% risk (or 1 in 2 chance) of passing the abnormal gene on to their child.
What is the BRCA gene mutation and how likely this is to cause genetic breast cancers in the person with the mutation?
Most inherited cases of breast cancer are associated with mutations in one of two genes: BRCA1 (BReast CAncer gene 1) and BRCA2 (BReast CAncer gene 2).
Everyone has BRCA1 and BRCA2 genes. The function of the BRCA genes is to repair DNA damage in a cell and keep breast, ovarian, and other cells growing normally. An inherited mutation in a BRCA1 or BRCA2 gene means that one of the copies of the gene is not working but that the other copy can maintain the normal function. It is when the second copy of the BRCA1 or BRCA2 gene acquires a mutation that both copies are now non-functional, and the wrong protein is made.
With two non-functional copies making the wrong protein, the ability of the cell to repair DNA damage is affected. If DNA damage cannot be repaired, but the cell remains alive, the cell may become cancerous by growing uncontrollably and forming a tumour mass. BRCA1 and BRCA2 gene mutations account for about 5-10% of breast cancer diagnoses in Australia today.
What percentage of the population have the BRCA gene mutation?
It is estimated that in Australia today, about 1 in 400 women are at the highest risk of breast cancer because they carry a BRCA1 or BRCA2 gene mutation. For these people, carrying a BRCA1 gene mutation is associated with an approximate 72% risk of developing breast cancer over the course of their lifetime. And they can have a risk of up to 44% of developing ovarian cancer. BRCA2 is associated with around a 69% chance of breast cancer and 17% chance of ovarian cancer of a lifetime.
Jewish women of eastern European ancestry (Ashkenazi) are more likely to carry a BRCA1 or BRCA2 gene mutation, estimated to be present in about 1 in 40 women. This is 20 times more common than in the general population.
Does the BRCA mutation cause any other types of cancers?
Mutations in breast cancer gene BRCA1 increases the risk of breast cancer, ovarian cancer, while BRCA2 increases the risk of breast cancer, ovarian cancer, prostate cancer, and pancreatic cancer.
What other genes are we aware of that cause breast cancer?
There are many genes associated with breast cancer, and our knowledge about these genes continues to increase. However, we still only know about half of these genes. In addition to BRCA1/2, those that we know about include PALB2, CHEK2, ATM, TP53, PTEN, RAD51 and BARD1.
You can get tested for the BRCA gene mutation. Can you get tested for any other breast cancer causing genetic mutations?
Yes, many of these genes can be tested for. Before having a test, it is important to understand the implications of a positive or negative test for oneself and one’s family, and indeed whether testing is necessary. This requires a thorough discussion with an appropriately qualified professional such as a clinical geneticist or genetic counsellor.
Are any of these other mutations more of a concern than a BRCA gene mutation when it comes to breast cancer?
The BRCA1 and BRCA2 gene mutations are the most common cause of genetic breast cancers. Other gene mutations may not increase the risk of breast cancer by as much as BRCA mutations – each needs to be assessed individually.
When should I consider getting genetic testing? Should everyone get it?
Genetic testing is often offered to women who are diagnosed with genetic breast cancers at an early age (35 and under), who have a strong family history or who are diagnosed with certain types of breast cancer such as ‘triple negative breast cancer’. If a gene mutation such as in BRCA1 or BRCA2 (the most common types) is identified, this can be associated with a family history of breast, ovarian, prostate and some other types of cancer. It is important to note that family history can come from your mother or father’s side of the family.
How do I go about getting genetic testing done? Where do I start?
Genetic testing is offered only through a Familial Cancer Clinic or appropriately qualified professional such as an oncologist. If a woman is referred to a Familial Cancer Clinic, the availability, limitations, potential benefits, and possible consequences of genetic testing will be discussed with her. If you are concerned about your strong family history of breast cancer, or you have a close family member with a BRCA gene mutation, speak with your doctor about a referral to a Familial Cancer Clinic.
How much does it cost?
In Australia, Medicare covers the cost of genetic breast cancers testing if an individual reaches a certain threshold for the likelihood of having a positive test. For those who are under the threshold, they can pay for testing after discussion with an appropriate health professional. The cost of the test is typically several hundred dollars, depending on which genes are being tested for.
What should you do if you get a positive result for one of the concerning genetic mutations? Should I get a mastectomy?
While a mastectomy is proven to be the most effective way in reducing breast cancer risk, particularly for those with a gene mutation, we understand that this isn’t an option for everyone. Other available options that may reduce the chance of developing cancer or improve the likelihood of detecting it earlier, include having yearly screening with breast MRI’s and regular mammograms, clinical breast examinations, paying close attention to how your breasts normally look, and engaging in healthy behavior such as regular exercise. Make sure to discuss your results and your options with your GP/ health care professional, as they are best placed to give you advice based on your personal situation.
Does a positive genetic mutation test affect things like life insurance/income insurance?
Private health insurance is not affected by a BRCA gene mutation. Other types of insurance such as life insurance can be affected, which should be discussed with a genetic health professional.
Is there a chance that a genetic mutation like this wouldn’t mean that I would get breast cancer?
Having a BRCA1 or BRCA2 gene mutation doesn’t mean you will be diagnosed with breast cancer and if one family member has a genetic mutation linked to breast cancer, it does not mean that all family members will have it.
How do I approach my children to discuss that I have a genetic mutation? What age should you have that conversation? What is the earliest someone should get tested?
This is another area that a genetic cancer clinic can support. There are many circumstances that impact the timing of discussions with children and other relatives, including the genetic mutation and the options for risk management.
What is your advice to people around managing anxiety when they get genetic testing and/ or when they get a positive result?
It’s important to have a strong support network around you when managing anxiety around genetic testing, particularly after receiving a positive result. Discussing your anxieties with friends, family, or a psychologist may assist you in managing any feelings of anxiety or concern that may arise.
Source @womenshealth.com.au: Read more at : womenalive.org
