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New genetic evidence for breast cancer -

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Reporter: Jennifer Macey

ELEANOR HALL: A large international study on breast cancer has found further genetic evidence for
the disease.

The study was led by Cancer Research UK and looked at the genetic make-up of more than 40,000 women
with breast cancer from 16 countries - including Australia.

The researchers found two more regions of the human genome that, if altered, can change a woman's
risk of developing breast cancer.

Jennifer Macey has our report.

JENNIFER MACEY: It's a massive international study.

One hundred scientists from 16 different countries analysed the DNA of 80,000 women, half with
breast cancer and half without.

After sifting through piles of statistical information, the researchers found two new genetic links
to breast cancer.

The findings have been published in the latest edition of Nature Genetics.

The University of Melbourne's Professor John Hopper is one of the Australian breast cancer
researchers who contributed to the report.

JOHN HOPPER: What has been discovered are markers in these regions which are associated with a
small increased risk.

On their own, they don't really matter a great deal, but what's exciting about this research is
that it's identifying new regions, new genetic regions, which have obviously got something to do
with breast cancer.

JENNIFER MACEY: Unlike the genes BRCA1 and BRCA2, which are responsible for up to 10 per cent of
breast cancer cases, these new genetic regions on their own aren't big risk factors.

But scientists say that when grouped with other genetic faults, they may increase the risk.

Professor Hopper says they now know of 13 genetic variants linked to breast cancer, but there could
be more.

JOHN HOPPER: In the fullness of time we may be able to do a number of tests and see what
constellation of genetic risk factors each woman has.

And then we also need to do the research to work out, given her level of genetic risk, what are the
appropriate prevention strategies and screening strategies that she should undertake.

JENNIFER MACEY: Dr Jennifer Byrne is a molecular biologist based at the Children's Hospital at

She says it's a significant study because so many women have been examined.

Yet she says it's a micro step, and studying for these new genetic variations is still a long way

JENNIFER BYRNE: Because I think there are clearly many more of these genes to be found, and the
only way that they can be found really is through these kinds of large studies that have the
statistical power that allow you to pick up weak effects by studying such large populations.

JENNIFER MACEY: But there are already women who are having double mastectomies...

JENNIFER BYRNE: Yes, that's right, yeah.

But those women have copies of genes that have a very strong association with breast cancer risk.

So those are women with BRCA1 or BRCA2 mutations.

But really, at this point, because the genes individually have weak effects, it's hard to see how
that would happen right now.

We would need to know the identities of more of these genes.

JENNIFER MACEY: And she says these genetic changes could be linked to other types of cancers - not
just breast cancer.

This is the hope of Professor Ian Olver, the CEO of the Cancer Council of Australia.

And he warns women against being alarmed.

IAN OLVER: At the moment women shouldn't rush out and ask for tests.

In fact, still probably the strongest factor is if they know they've got a family history, rather
than the subtleties of which genes are altered.

ELEANOR HALL: That's Professor Ian Olver, the CEO of the Cancer Council of Australia, ending that
report by Jennifer Macey.