Breakthrough suggests breast cancer 'holy grail' within reach

Angelina Jolie famously removed both her breasts when she found out she has the BRCA1 gene (Reuters)
Angelina Jolie famously removed both her breasts when she found out she has the BRCA1 gene (Reuters)

Researchers have discovered an existing drug used to fight osteoperosis could prevent breast cancer from developing.

Women who have the BRCA1 gene mutation are at high risk of developing breast cancer. Hollywood star Angelina Jolie infamously had both of her breasts removed after finding out she had the mutation.

But researchers in Australia have found denosumab, currently used to treat osteoporosis and breast cancer that has already spread to the bone, could stop the cancer even establishing a foothold in the first place.

PhD researcher Emma Nolan says there are presently limited options for prevention, with the primary options removal of the breasts and ovaries, or heightened surveillance.

"We were interested in identifying an alternative option, a non-surgical approach for these women to prevent breast cancer."

The breakthrough came when the researchers found cancer precursor cells in BRCA1 breast tissue contain a protein called RANK -- which denosumab is already known to inhibit.

"We therefore investigated what effect RANK inhibition had on the cancer precursor cells in BRCA1-mutant breast tissue," says oncologist Geoff Lindeman.

Denosumab "switched off" the cancer cells' growth in donated breast tissue, and slowed its growth in lab testing.

"By thoroughly dissecting how normal breast tissue develops, we have been able to pinpoint the precise cells that are the culprits in cancer formation," says Professor Jane Visvader.

"It is very exciting to think that we may be on the path to the 'holy grail' of cancer research, devising a way to prevent this type of breast cancer in women at high genetic risk."

Auckland mum of two, Kirsty Walters, 41, carries a faulty BRCA1 gene. It runs in her family, which means she's at high risk of developing aggressive breast cancer. To prevent it she opted to have both her breasts and ovaries removed.

"It is quite a drastic step," she says, "but it wasn't a difficult decision for me because I'd lost my mum and I'd lost other family members to cancer."

The other alternative for women at high risk is to have regular screening.

"I just wanted to get on with life, and I felt that in my mind that if I just had screening that I would always be worried."

Although she no longer worries for herself, Ms Walters holds concern that her two daughters, aged five and seven, will one day test positive for the faulty gene.

"I rest in the knowledge that there will be some medical advancements that will either mean that they won't get cancer or that there's some other preventative measures."

New Zealand Breast Cancer Foundation CEO Evangelia Henderson is excited by the findings.

"Whilst it's still a small step and it's in a laboratory, it might be another option for women in the future who have the BRCA gene mutation to have another option for preventing the onset of breast cancer."

She says the mutation is a ticking time bomb, and those with it are at high risk of getting breast cancer.

"The only way they can prevent it is to surgically remove the breast and so that's the very drastic measure. It's painful -- one obviously has to go through obviously losing the breast, but also going through hormonal treatment, and making a 40-year-old woman or younger go through menopause, it's not a nice thing."

Denosumab isn't an approved medicine for breast cancer prevention however, so clinical trials will still be needed to verify its effectiveness.

The research was published Tuesday in journal Nature Medicine.