Breast cancer discovery aims to block tumour spread

Exciting new news for Breast Cancer:

ELEANOR HALL: Let's head now to Melbourne where a team of scientists says it has identified the way that breast cancer spreads around the body.

The researchers at the Monash Institute of Medical Research and Peter MacCallum Cancer Centre say the disease spreads secretly by switching off the immune system and hiding in the blood stream.

The head of Cancer Australia says understanding how cancer spreads is like the Holy Grail of medicine and that the discovery has great potential.

In Melbourne, Alison Caldwell reports.

ALISON CALDWELL: Each day around Australia, 38 women are diagnosed with breast cancer. There are currently 70,000 women fighting the disease and many of them will beat it.

Beyond that, a key concern for them is the possibility that the cancer cells could spread to the bone or metastasise.

While survival rates for primary breast cancer have steadily increased over the past 30 years, mortality rates remain high when cancer has spread to secondary sites, such as the brain, lung and liver.

The new research by the team from the Peter MacCallum Cancer Clinic in Melbourne is important because it focuses on the spread of secondary cancer.

Dr Belinda Parker is with the Metastasis Research Laboratory at Peter Mac.

BELINDA PARKER: We've found a way that breast cancer cells can hide from the immune system to enable them to spread to other parts of the body such as the bone. And we're quite excited by this because therapies that are currently already available can be used to switch this immune signal back on, and we've found that that actually prevents the spread of cancer to bone.

ALISON CALDWELL: What's the potential of that research?

BELINDA PARKER: So we've found that cancer cells can usually produce signals, the same signals that are produced when we have a bacterial or a viral infection and that these cells that lose these signals are those that can spread.

And what's quite good about this finding is that there are already therapies in the clinic used for hepatitis, HIV, and other cancers like melanoma, that can switch this signal back on and cause the immune system to react to the cancer cells.

ALISON CALDWELL: So you're hoping that you might be able to apply the same thing then to women with breast cancer?

BELINDA PARKER: Yes, we're hoping that we can look at a breast cancer patient's tumour or cancer and if they have lost these immune signals, we think that those breast cancer patients would benefit most from these therapies that switch the signals back on.

ALISON CALDWELL: Is this something that could become a reality for women in the next five years, let's say?

BELINDA PARKER: Yes the well the advantage of our findings is that not only is there a therapy available that's used in humans for other diseases that will switch these signals back on, but we now have a way of determining which patients would benefit most.

So in the next year or so we just want to make sure that we're selecting the patients that will benefit from these therapies the best way we possibly can.

ALISON CALDWELL: What's known about the percentages of women who will develop secondary cancer?

BELINDA PARKER: More than 80 per cent of breast cancer patients will never develop spread to a distant site, however, for the remaining patients that to develop spread, most of them will develop spread to their bones and this is very difficult to treat.

ALISON CALDWELL: The research published in Nature Medicine has been welcomed as a promising breakthrough.

Dr Helen Zorbas is the CEO of Cancer Australia.

HELEN ZORBAS: If you like it's a bit of a Holy Grail being able to understand what it is that triggers spread beyond the breast and what this discovery tells us is that cells have been escaping immune recognition and are now being able to be unmasked and able to block that spread and growth at least in these mice models at this point.

I think the potential is there to take what we already know has worked in other diseases and in other metastatic cancers, such as melanoma, into the breast cancer setting and obviously that's the hope here. But we also know that there may be other factors that are impacting on the spread and growth of cancer, it may be that it's in fact a multitude of effects that are at play here.

So this is very exciting and very important work in trying to better understand the immune pathway in breast cancer cells that may be critical to spread of disease to bone.