Australian scientists have made a breakthrough in understanding why women with a specific gene mutation are more likely to develop breast cancer, a research study revealed on Monday.

Women with a gene named BRCA1 are known to have about a 65 percent lifetime chance of developing the cancer, and researchers at Melbourne's Walter and Eliza Hall Institute have traced the cause to an unexpected source.

It had been thought the cancer risk was associated with stem cells specific to the breast but instead the problem was found to be linked to the next phase -- or "daughters" -- of these stem cells known as luminal progenitor cells.

"Our gene expression studies have revealed that BRCA1 breast tissue and basal breast tumors are more similar to normal luminal progenitor cells than any other cell type in the breast," Associate Professor Jane Visvader said.

"This places the spotlight on errant luminal progenitors, rather than breast stem cells."

The research, published in the international journal Nature Medicine, represents a major shift in the way breast cancer is understood to develop and points to a new avenue for targeted treatments.

"Hopefully this will lead to new, tailored therapies for the next generation of women," Lindeman said.

(Xinhua News Agency August 3, 2009)