Everything you need to know about BRCA1 and BRCA2

If you or someone in your family has gone through breast cancer or ovarian cancer, it may raise your concerns about whether this risk has been passed down through your family. It is important to understand your family history of cancer and to ask your doctor if you have any concerns, in order to provide you and your family with the best possible chance of preventing cancer from developing.

Factors influencing a predisposition to breast cancer

Unfortunately, there’s no one reason a person may develop breast cancer. Often it is a combination of factors. Below are some factors that may increase your predisposition to breast cancer.1

  • Genetic testing has positively indicated you carry the BRCA1 or BRCA2 mutation gene
  • You had your first child at a later age
  • Your menstrual cycle started young
  • You or a relative were diagnosed with ovarian or breast cancer prior to menopause
  • You have elevated blood levels of female hormones post-menopause
  • You used hormone replacement therapy for an extensive period after menopause
  • Pre-cancerous conditions appeared on your breast biopsy, including atypical ductal or lobular hyperplasia, or lobular carcinoma in situ of the breast
  • Hereditary cancer syndrome, such as Cowden syndrome, Peutz-Jegher syndrome or Li-Fraumeni syndrome appear in your family history

Factors influencing a predisposition to ovarian cancer

Ovarian cancer is predominately found in women over 50-years-old, and occurs when a cancerous tumour develops in one or both ovaries. While this particular cancer is not very common in younger women, young women are still diagnosed and a small percentage of ovarian cancer cases are caused by gene mutations.3

Whilst there is no one cause of ovarian cancer, risk factors include: 2

  • Genetic testing has positively indicated you carry the BRCA1 or BRCA2 mutation gene
  • Women with few pregnancies or who have never been pregnant
  • A family history of the disease
  • A high-fat diet
  • Early menarche and late menopause

What you need to know about BRCA1 and BRCA2

Both men and women carry the BRCA genes—BRCA1 (BReast CAncer1) and BRCA2 (BReast CAncer2)—which serve as protection from breast and ovarian cancer in women, and breast and prostate cancer in men. It’s only when these genes are damaged that they increase the predisposition to breast and ovarian cancer. Other cancers that are impacted by harmful mutations of the BRCA genes include fallopian tube cancer, peritoneal cancer and pancreatic cancer.

Should you test positively for BRCA1 or BRCA2 through genetic testing, your risk for getting breast and ovarian cancer is much higher than the general population but it does not mean you or your family will get these cancers.

For women who have inherited a faulty copy of the BRCA1 gene the lifetime risk of developing breast cancer is approximately 70% and the lifetime risk of developing ovarian cancer is approximately 45%.3,4 For women who have inherited a faulty copy of the BRCA2 gene the lifetime risk of developing breast cancer is approximately 70% and the lifetime risk of developing ovarian cancer is approximately 20%.3,4 As both BRCA genes are considered high risk factors in the development of cancer, it is important to educate yourself around hereditary cancer and genetic testing.

To reduce the risk of developing cancer, you should maintain a healthy diet and lifestyle through regular exercise, reducing alcohol intake and stopping smoking. Age appropriate screening is also important. You are encouraged to receive breast screening once every two years if you are aged 50 and above. Regular breast self-examinations should be conducted monthly from the age of 20, one week after the end of your menstruation when your breasts are less tender and lumpy, to look out for any changes in your breasts.

Currently there is no single reliable screening test to diagnose ovarian cancer. Typically a blood test to test for CA125 – a common marker for ovarian cancer can be done, along an ultrasound scan. However ovarian cancer is usually diagnosed during surgery. Therefore knowing your body and being aware of any changes and symptoms is important.

What is genetic testing and who is it for?

If you meet any of the predisposing criteria for cancer (above), and are assessed by a specialist to be predisposed to this cancer, you’ll likely have the opportunity to undergo genetic testing. Genetic testing is also encouraged for women diagnosed with invasive epithelial ovarian cancer, fallopian tube cancer, primary peritoneal cancer and breast cancer.

Genetic testing will determine whether you are a gene carrier of either the BRCA1 or BRCA2 gene mutation. The procedure is non-invasive and performed through a blood test.

Genetic counselling will be provided before and after the test by a specialist health care professional.

Pre-test counselling will include:

  • Documenting your family history in detail, done by your genetic counsellor / specialist
  • Discussion on relevant tests and their accuracy
  • How you will benefit from genetic testing
  • An outline of available medical treatments once you receive your test result
  • The emotional and psychological impact of genetic testing and the results
  • Risks associated with passing on the altered gene to your children

We understand that this process can be emotional, which is why we encourage you to discuss genetic testing with your doctor as well as your family or relatives early on. Your doctor will also advise you to speak with your genetic counsellor about any reservations or emotions you feel before, during or after the genetic testing process.

Following the test, you’ll be notified by your genetic counsellor who will discuss when you should schedule a follow-up appointment.

Possible results from genetic testing include:

  • Positive results – a positive result will indicate that you have a BRCA1 or BRCA2 mutation and are at greater risk for certain cancers, which may also have implications for family members. Your genetic counsellor will discuss what this means for you and your family.
  • Negative results – your genetic counsellor will discuss your results and whether this is a true negative, which means that you don’t carry the BRCA1 or BCRCA2 mutation. Negative results may also be unclear, as there is a very low potential that the genetic testing will miss a known BRCA1 or BRCA2 mutation in people with a family history.
  • Variant of unknown significance – in some instances, your results may find genetic mutations in BRCA1 or BRCA2 that have not previously been associated with an increased cancer risk. Your genetic counsellor will discuss what this means for you.

Icon Cancer Centre Hobart is proud to offer a dedicated private genetic counselling service within their centre. For more information on this service, click here.

What happens if you test positively for a BRCA1 or BRCA2 gene mutation?

If you have inherited a faulty gene that has caused your cancer, your doctor will be able to talk you through the next steps and connect you with the right specialists. You’ll also be informed about any adjustments to your follow-up care plan based on your test results.3,4

When a faulty gene presents an increased risk of ovarian or breast cancer, genetic testing may be offered to other family members. Any family members also inheriting a faulty gene should speak with their doctor about how they can further reduce their risk.3,4

Some women who test positive as gene carriers but have yet to be diagnosed with cancer may choose to undergo risk reducing surgeries such as a bilateral mastectomy to remove both breasts and lower the risk of breast cancer. Otherwise, those 30 years and older may receive annual MRI breast checks and/or drug treatment (where necessary). To reduce the risk of ovarian cancer, women may consider having their ovaries and fallopian tubes removed.3,4  It is important to speak to your doctor or genetic counsellor before commencing any risk reduction measures.

References

To view the full list of references, click here.
  1. Breast and Ovarian Cancer Genetics and Prevention. Dana Farber Cancer Institute. Retrieved 17th March, 2020. https://www.dana-farber.org/cancer-genetics-and-prevention/syndromes-genes-and-programs/breast-and-ovarian-cancer-genetics-and-prevention/
  2. Singapore Cancer Society. (n.d). Ovarian Cancer. Retrieved 4 June, 2019. https://www.singaporecancersociety.org.sg/learn-about-cancer/types-of-cancer/ovarian-cancer.html
  3. Facts for people and families with a faulty BRCA1 gene. eviQ. Retrieved 19 October, 2020. https://www.eviq.org.au/cancer-genetics/consumer-information/3426-facts-for-people-and-families-with-a-faulty-b
  4. Facts for people and families with a faulty BRCA2 gene. eviQ. Retrieved 19 October, 2020. https://www.eviq.org.au/cancer-genetics/consumer-information/3427-facts-for-people-and-families-with-a-faulty-b

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