Everything you need to know about BRCA1 and BRCA2

If a relative or someone in your family has gone through breast cancer or ovarian cancer, it may raise your concerns about whether you’re at greater risk of developing breast cancer yourself. It is important to understand your family history of cancer and to ask your doctor if you have any concerns.

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

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.

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 do 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.

For women who have inherited an altered gene (around 5% of women diagnosed with breast cancer⁶), your lifetime risk of developing breast cancer is 60-90% for BRCA1 and 45-85% for BRCA2⁴. BRCA1 and BRCA2 genes are also responsible for 85-90% of hereditary ovarian cancers. ³ 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.

Should you test positive 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 will get these cancers.

To mitigate the risk of developing cancer, we highly advise a healthy diet and lifestyle through regular exercise, reducing alcohol intake and stopping smoking. Age appropriate screening is also important. You are encouraged to consult the doctor for breast screening yearly if you are aged 40 to 49-years-old, and once every two years for women 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. For more information on breast cancer screening, click here.

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 at surgery. Therefore knowing your body and being aware of any changes and symptoms is important. For a range of screening services including breast cancer screening and testing for cancer markers, we encourage you to visit Icon Health Screening.

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 altered genes BRCA1 or BRCA2. The procedure is non-invasive and performed through a standard blood test. Your blood is next examined under a microscope where lab specialists will assess the DNA within your white blood cells.

Genetic counselling will be provided before (pre-test) and after (post-test) 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 oncologist (if diagnosed with cancer) or 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.

Post-test counselling will 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 (VUS) – in some instances, a genetic result may find genetic mutations in BRCA1 or BRCA2 that has not previously been associated with an increased cancer risk. Your genetic counsellor will discuss what this ambiguous mutation

If you have inherited a faulty gene that has caused your cancer, your next steps should be discussed with your oncologist which will connect you with the right specialists. These practitioners are qualified to discuss your case in greater detail and provide the next steps in your treatment. You’ll also be informed about any adjustments to be made to your follow-up care plan based on your test results.⁵

When a faulty gene presenting an increased risk to ovarian or breast cancer is identified, genetic testing may be offered to other family members. Any family members also inheriting a faulty gene will have the opportunity to speak with an oncologist on how they can further reduce their risk.⁵

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 bilateral mastectomies to remove both breasts. Otherwise, those 30 years and older are highly advised to perform 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, or if recommended, a hysterectomy (removal of the uterus).³ There is evidence that women who have used the oral contraceptive pill for five years or more have a reduced risk of developing ovarian cancer, however this is not suitable for all women.³ It is important to speak to your doctor or genetic counsellor before commencing any risk reduction measures.

Icon’s Young Women Cancer Program connects women to genetic counsellors for further information and whether it is suitable to undergo testing procedures. For young women diagnosed with either breast or ovarian cancers, our oncologists are also equipped to carry out genetic testing for patients following comprehensive genetic counselling.