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The news that 72 new genes associated with breast cancer were identified by scientists around the world, including five teams from the University of Toronto, is considered a major step forward in how we understand the disease.

Gary Bader, a professor at U of T’s Donnelly Centre for Cellular and Biomolecular Research and the departments of molecular genetics and computer science, says there are important short- and long-term implications of the findings.

The long-term hope, Dr. Bader writes in this week’s edition of , the Toronto Star’s weekly column created by U of T medical experts, is that “the more we know about the biology of breast cancer, the faster we will be able to stop it from starting and spreading.”  

The discoveries, he adds, could ultimately help develop drugs that prevent breast cancer altogether.

In the meantime, he writes, the findings provide an important step forward in the development of “precision medicine,” instead of the one-size-fits-all approach doctors currently use.

The discoveries can help predict who is most at risk for breast cancer, he writes. Right now, women with a family history of certain cancers can get the BRCA genetic test to see if they’re at high risk of developing breast and ovarian cancer. But, he writes, the BRCA mutations “are very rare – the vast majority of women who develop breast cancer are not BRCA-positive.”

The 72 new genes, which were discovered after scientists studied blood samples of 275,000 women,  aren’t as risky as BRCA, Bader writes, but are more common.

"Some of these mutations may only raise your chance of getting breast cancer by a few percentage points – not 80 per cent as in the BRCA mutations – but you may carry enough of them to add up to a high risk. Alternatively, you may have one that is more sensitive to environmental risk factors such as smoking and obesity."