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GENETIC TESTING
FOR BREAST CANCER

Cancer Geneticist Associate Professor Judy Kirk explains who should get genetic testing for breast cancer, what exactly a ‘strong family history’ means and how you can get tested.

What Is Genetic Testing?

Should you get genetic testing for breast cancer?

Preventative genetic testing is only recommended for a small number of women with known gene mutations in their immediate family or who have a strong family history.

However, for these women, genetic screening can be incredibly beneficial.

Associate Professor Judy Kirk is a cancer geneticist at the Familiar Cancer Service at Westmead Hospital.

She says genetic testing is looking for a mistake in the gene that causes a high risk of breast and ovarian cancer within a family.

“It’s testing that’s done on blood, in a family with a pretty strong family history of breast cancer where we would start by testing an affected family member.”

“Usually we test a women who’s had either breast or ovarian cancer, and we search a number of different genes to try and find a fault or mutation, that’s passed down through the family that causes that high risk,” she said.

“When we do that, there are a number of different genes that we can test and the ones that relate to breast cancer are two genes we’ve known about now for over 20 years. One of them is called BRCA1, the breast cancer one gene, and the other called BRCA2, the breast cancer two gene, and more recently it’s been found that mutations in another gene, known as PALB2 also cause a higher risk of breast cancer.”

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Cancer Geneticist Associate Professor Judy Kirk explains who should get genetic testing, what exactly a ‘strong family history’ means and how you can get tested.

What Is A Strong Family History?

Associate Professor Kirk said a ‘strong family history’ is when there are three or more affected family members on one side of the family. However sometimes an individual will not know this information, or their family is predominately male. Associate Professor Kirk said in these instances, there are other factors that come into play.

“There are other things that we might look for, and they would include: early age at breast cancer diagnosis, the presence of triple negative breast cancer in a young woman, less than 50 years of age at diagnosis, ovarian cancer specifically high grade, invasive epithelial ovarian cancer. Most women with that type of cancer is now offered a genetic test,” she said.

Associate Professor Kirk said it is standard practice to first test the genetics of a family member who has been affected by breast cancer and then subsequently decide if it is worth testing other family members.

You can still choose to be tested if your immediate affected family member has died or is not in a position to be tested.

However, Associate Professor Kirk said the information gained from the test can only be used in individual instances and cannot tell the story for the whole family.

“The thing is if you find nothing in that women, that’s quite reassuring but you still don’t know whether there is a genetic fault in the family.”

“So perhaps that young woman will be tested, but her sisters are no better off. Each sister would have to have that genetic testing in order to reassure themselves about themselves and their families.”

Associate Professor Kirk said it is also a misconception that inherited genetic mutations are more common on the mother’s side of the family.

“Very often its distressing to hear people who say, ‘they didn’t worry about my family history because it’s on my dad’s side’.”

“It’s equally important and so while we don’t add the two sides of the family together, we always take the mums side, we always take the dads side and, in a way, we act on the side that looks more worrisome.”

What Happens If The Genetic Test Comes Back Positive?

If your test come back positive for a gene mutation, then a risk management plan can be put in place.

“For example, someone with the BRCA1 gene would start their breast screening from age 30,” Associate Professor Kirk said.

“They usually start it in a risk management clinic where there’s special expertise and the availability of breast MRI for screening rather than simply mammography ultrasound and of course, those women are also given the opportunity risk reducing surgery for the breast tissue, which is taken up by maybe about 30% of high risk women.”

The BRCA gene mutations also increase your risk of developing ovarian cancer and so this will also be taken into consideration if a woman is tested positive for a BRCA gene mutation.

“Many choose to have screening, but I think the more important thing is that these women, if they have a BRCA1 or BRCA2 mutation are also at very high risk of ovarian cancer.”

“There is no screening test for that and so once they’ve finished their family, by about age 30, the best approach at the moment is to remove the ovaries and fallopian tubes and that is the single most important thing that saves lives in these families.”

“So it’s very important to identify these women because we can save lives from cancer if we look after them appropriately.”

Other Genetic Breast Cancer Risk Factors

If your test come back positive for a gene mutation, then a risk management plan can be put in place.

“For example, someone with the BRCA1 gene would start their breast screening from age 30,” Associate Professor Kirk said.

“They usually start it in a risk management clinic where there’s special expertise and the availability of breast MRI for screening rather than simply mammography ultrasound and of course, those women are also given the opportunity risk reducing surgery for the breast tissue, which is taken up by maybe about 30% of high risk women.”

The BRCA gene mutations also increase your risk of developing ovarian cancer and so this will also be taken into consideration if a woman is tested positive for a BRCA gene mutation.

“Many choose to have screening, but I think the more important thing is that these women, if they have a BRCA1 or BRCA2 mutation are also at very high risk of ovarian cancer.”

“There is no screening test for that and so once they’ve finished their family, by about age 30, the best approach at the moment is to remove the ovaries and fallopian tubes and that is the single most important thing that saves lives in these families.”

How Do You Get Tested?

If you have a strong family history and would like to be tested, Associate Professor Kirk said to contact your local familiar cancer clinic.

“Most of this genetic testing is done through specialist clinics, either private or public and the genetic testing is covered by the system either Medicare or by the state health departments where it’s quite likely that we’ll find something, perhaps an over 10% chance that we’re going to find something.”

“If the chance is less than that, it tends not to be covered by the system and in that case the patient can pay for that testing,” she said.

“Again, it’s usually done through a specialist familiar cancer service, so that they understand the limitations of the testing in that circumstance and the implications of insurance and for other family members etc.”

“So, they’re fully informed before the testing about what could expected, what genes are going tested and what could be the impact of finding something or finding nothing in some situations.”

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Associate Professor Judy Kirk

Associate Professor Judy Kirk is a cancer geneticist at the Familiar Cancer Service at Westmead Hospital.

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