BRCA gene

We all have a material called DNA in our body. We inherit half our DNA from our mother, and half from our father. This means we all have 2 copies of the BRCA1 and BRCA2 genes. Genes are made up of sections of DNA. Genes give instructions (almost like a recipe) for proteins that your body needs to grow and do its job.

BRCA1 and BRCA2 (BReast CAncer gene 1 and BReast CAncer gene 2) make proteins that protect your body against cancer. If these genes have a pathogenic variant (disease-causing error) in them, they stop working and you lose some of that protection (like if there was a typo in a recipe which changed the instructions). Genetic testing helps determine if you were born with a BRCA pathogenic variant.

Women born with a variant in a BRCA gene are at increased risk for breast, ovarian, and sometimes pancreatic cancer. Men are at increased risk for breast, prostate, and sometimes pancreatic cancer.

Cancer is common in our community. About 1 in 10 women (10%) in Aotearoa New Zealand develop breast cancer over their lifetime. Importantly, most cancer occurs due to age, chance, and environmental factors and it's not usually hereditary. Only about 5% of all breast cancer is hereditary (see the NSW Centre for Genetics Education page(external link) on heritable breast cancer for more information).

Genetic testing is best started in a family member who has had cancer. If there is a hereditary cause for cancer in the family, we are more likely to find it in an affected person. If there are no living biological family members who have had cancer, then it's sometimes appropriate to test an unaffected individual, although this is determined on a case-by-case basis.  

Typically, genetic testing for the BRCA genes is indicated for people who have had breast or ovarian cancer at a young age or if there are multiple people in the family with breast, ovarian, prostate, or pancreatic cancer. Some populations, such as people with Jewish ancestry, may also be more likely to have a BRCA variant than the general population.

The current genetic testing process involves discussing the implications of genetic testing with a genetic counsellor(external link). Genetic counsellors are genetics experts who discuss your family history, order genetic testing where appropriate, and help you adapt to the implications of genetic test results. Genetic testing can't always exclude the possibility of a hereditary cancer syndrome, so it's best to have an expert to answer your questions!

If genetic testing is appropriate for you and you want this, a blood sample usually needs to be provided. Then the lab can use this to extract your DNA for genetic testing.

If you are part of a family where a BRCA variant has already been identified, you can contact the Genetic Health Service NZ(external link) (who are part of the public health system) directly and provide the required details. There are also private genetic services available in Aotearoa New Zealand.

If your family was tested overseas, you will need to provide a copy of a genetic test report before any testing can be arranged. Genetic testing for family BRCA gene pathogenic variants is available once an individual is 18 years of age or older.

If you have cancer and you have a variant in a BRCA gene, your oncology team will be informed. If you don't have cancer, you'll be referred to a breast specialist or gynae-oncologist, where appropriate, to discuss ongoing risk management and surveillance. Younger people may have to discuss referral to the necessary specialists with their healthcare provider once they have reached the age that referral is recommended.

The following guidelines are sourced from eviQ(external link) and are general guidelines only. Please discuss with a medical professional what surveillance (checking for early signs of cancer) or surgery may be best for you.

Breast Cancer

Women at high risk of developing breast cancer are offered annual breast screening, usually from age 30 unless there are younger diagnoses in the family. Mammography, MRI, or ultrasound are used for this and surveillance will be tailored to the individual.

Some people choose to have prophylactic mastectomy (removal of healthy breasts). The risks of surgery are weighed against the remaining lifetime risk for breast cancer.

Prostate Cancer

An annual blood test for prostate specific antigen (PSA), and discussion about digital rectal examination, should be offered to male BRCA2 carriers from age 40. If your PSA is above normal over several tests you will be referred to a urologist.

Ovarian Cancer

There is currently no effective surveillance available for early detection of ovarian cancer. To reduce the risk for ovarian cancer, prophylactic surgical removal of the ovaries from age 35-40 years, and after you've had your children, is suggested.

Pancreatic Cancer

There's also currently no effective routine surveillance available for early detection of pancreatic cancer. Therefore, the current recommendation for those with a BRCA2 variant is to not smoke, as smoking increases risk for pancreatic cancer.

See the Cancer Society of New Zealand webpage reduce your risk of cancer(external link) for general advice about lowering cancer risk.