What you should know about testing for BRCA breast cancer genes

Breast cancer is one of the most common cancers affecting women, with South African woman having an approximate lifetime risk of 1 in 35. While breast cancer is far more common in women, it can affect men too.

The American Cancer Society estimates that 5-10% of breast cancer is hereditary. For those who have family members diagnosed with breast cancer, genetic testing can help doctors to assess your risk. The tests are conducted to test for any mutations to the BRCA1 and BRCA2 genes that would put you at an increased risk of breast cancer.

Recently Angelina Jolie underwent a preventative double mastectomy, inspiring women around the world to have their breast cancer risk assessed.

We contacted Professor J.P Apffelstaedt, the Associate Professor of Surgery at the University of Stellenbosch and Head of the Breast Clinic at Tygerberg Hospital to answer some questions you may have about genetic testing for breast cancer:

1. What age should you go for genetic testing to see if you are at risk of breast cancer?

As the mutated gene is present at birth, one can be tested at anytime, however a regular breast management regime should begin from the age of 20 and genetic testing with counselling, is usually only indicated if you are at very high risk of being carrier of a disease-causing mutation. As the risk of the disease in material only after age of about 20, the patients must be informed possible outcomes and consequences of testing. This requires them to be legal majors as otherwise it would be unethical to take decisions with far-reaching consequences that the patient then later is not in agreement with. See also below.

Watch: Debunking cancer myths with Professor J.P Apffelstaedt

2. If you are genetically pre-disposed to getting breast cancer, should you have a mastectomy?

If the results are positive the person can be continuously monitored to ensure early detection of breast cancer if it arises, or they could undergo a mastectomy, which will reduce the risk of breast cancer by up to 90%. However, patients need to realise this is a life changing procedure, for example it’s not possible to breast feed after a mastectomy, and it does not guarantee a cancer-free future as you cannot remove all breast tissue during surgery. So each case is different and the patient should be advised and counseled accordingly.

3. Do the tests only check for BRCA1 and BRCA2 mutations?

Yes, everyone has BRCA1 and BRCA2 genes. The function of the BRCA genes is to repair cell damage and keep cells growing normally; but when these genes contain abnormalities or mutations that are passed from generation to generation, the genes don't function normally and cancer risk increases, as they no longer assist in preventing uncontrolled growth of tumours.

4. How much does having a BRCA1 or BRCA2 gene mutation increase a woman’s risk of breast and ovarian cancer?

A positive test result in BRCA1 or BRCA2 means that the person has a genetic mutation that increases cancer risk. Women carrying mutations of the BRCA genes are about five times more likely to develop breast cancer than those without. This is because normal BRCA genes help suppress tumours, but when they’re mutated they don’t assist in preventing uncontrolled growth. A study suggests that women with a faulty BRCA1 gene typically have a 60 - 90% risk of getting breast cancer during their life, compared to a 12% risk for the average woman and a 30% to 45% lifetime risk of ovarian cancer. A positive BRCA2 result gives a woman a 50% to 70% lifetime risk of breast cancer and a 10% to 20% lifetime risk of ovarian cancer.

Read: A focused approach required for determining cancer risk
5. What other cancers have been linked to mutations in BRCA1 and BRCA2?

Women with an abnormal BRCA1 or BRCA2 gene also have an increased risk of developing colon, pancreatic, and thyroid cancers, as well as melanoma.

6. Who should consider genetic testing for BRCA1 and BRCA2 mutations?

You are substantially more likely to have an abnormal breast cancer gene if:

•    You have first-line blood relatives diagnosed before age 50.)
•    There is both breast and ovarian cancer in your family, particularly in a single individual.
•    Women in your family have had cancer in both breasts.
•    A man in your family has had breast cancer.
•    You are of Ashkenazi Jewish (Eastern European) heritage.
However, mutations in BRCA1 and BRCA2 only cause about one in twenty of breast cancers so just because you don’t have the gene mutation doesn’t mean you’re immune. In fact 70 – 80% of women who have breast cancer have no family history of the disease.

7. What are your other options? (treatment, chemo, lifestyle changes, etc)

Diet is thought to be partly responsible for about 30% to 40% of all cancers. But diet alone is unlikely to be the "cause" or "cure" of cancer. Physical activity, a healthy diet (particularly one low in fat and high in vegetables and fibre), and a healthy weight reduce the risk of breast cancer or the cancer coming back by up to half. As we know, some risk factors for breast cancer cannot be modified, such as age and gender; however other factors such as diet, physical activity and smoking can be.

8. Where can people go for genetic testing?

Any centre that specialises in breast health or a genetic testing company such as Gknowmix:.

9. How does genetic testing work/how is it performed?

In South Africa, the test for the BRCA1 and BRCA2 genes has been commercially available to the general public since 2005 . A blood sample is required for these tests, and genetic counseling is recommended before and after the tests.

10.   How quick can you get results?

If you have one of the mutations common in the South African population, results are usually available within a week. If a novel mutation is looked for , testing the entire gene can take up to 3 months.

11.   What does genetic testing for breast cancer cost –approximately?

Currently, in the public sector genetic counselling and testing is offered in the major academic centres free for indigent patients. In the private sector, testing for common abnormalities is about R 1 500, whereas full gene sequencing is about R 10 000– 15 000.

12.   If mastectomy is the only option, does breast reconstruction happen immediately or is there a waiting period?

We always offer immediate reconstruction.

13.   Should men also go for genetic testing?

Yes, if they have a predisposition of cancer within the family. Men who have an abnormal BRCA2 gene have a higher risk for breast cancer, prostate cancer and still other cancers than men who don't - about 8% by the time they're 80 years old, which is about 80 times greater than average.

Read: Breast cancer outcomes vary according to race

14.   Are mutations in BRCA1 and BRCA2 more common in certain racial/ethnic populations than others?

Eastern European heritage carries a greater risk of having a mutated BRCA gene.

15.   Is there anything new in terms of genetic or other testing, and in breast cancer detection and treatment in general?

No – nothing major over and above what was known last October.

Read More:
Tattoos help conceal breast reconstruction scars
Unhealthy insulin levels may boost breast cancer risk
Many breast cancer patients lack info on their condition

Image: Woman analyses genetic tests for reactions from Shutterstock
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