AUSTRALIAN researchers have found a ''genetic switch'' that could open up new treatments for breast cancer.

The switch allows scientists to change breast cancer cells and make them more responsive to treatments such as anti-oestrogen therapies.

Outlined in the journal PLOS Biology, researchers from the Garvan Institute of Medical Research in Sydney found the molecule, known as ELF5, can turn genes on or off.

By manipulating it, the breast cancer cell's sensitivity to anti-oestrogen drugs used to treat breast cancer can be increased.

''We've made a discovery that concerns the basic biology of breast cancer,'' said Chris Ormandy from the Garvan Institute. ''ELF5 determines whether cells will respond to oestrogen therapy or not.''

Oestrogen plays a key role in breast cancers. Women who do not experience much oestrogen, either because they start menstruating later in life or begin menopause early, have a lower risk of breast cancer.

Led by Professor Ormandy in collaboration with colleagues Maria Kalyga and David Gallego-Ortega, the finding establishes for the first time that there is a link between the molecule and breast cancer.

Found in all breast cells, the molecule was discovered by Professor Ormandy's team in 1999. In 2008 his group showed it triggered milk production in women.

Made with British researchers, the latest discovery raises the potential for drugs designed to reduce the amount of the molecule in those cancer cells dependent on ELF5 for proliferation. Further research could also reduce the incidence of patients undergoing ineffective treatment.