A global team of scientists, including researchers from several Canadian universities, has discovered a further 72 genetic variants that put women at risk of developing breast cancer.
The addition of these commonly inherited genetic variants to the 180 already known is thought to total some 18% of the associated familial risk for breast cancer.
“These new variants substantially expand the number of genes and pathways that are involved in breast cancer development, and these represent multiple new avenues of research to learn how to treat breast cancer,” says Gary Bader, a professor at the University of Toronto.
Global collaborations on monumental levels of data
Some 550 researchers from 300 universities spread across six continents analyzed the genetic data of approximately 275,000 women. Around half of these women were living with a cancer diagnosis.
In these types of genetic studies, scientists look for “loci” – DNA regions – that increase the risk of developing a disease. Loci can contain disease-associated genes or DNA sequences that lack instructions for making proteins but still regulate genetic activity.
The critical advancement in this study was how researchers used a massive amount of genomic information to better link up genetic variants to the genes they act upon.
Variants are identified as an alternate spelling in the DNA code and can be scattered throughout a genome. Most of these new variants were discovered in gene-regulating loci, where the team found distinct patterns related to breast cancer.
Co-author and Harvard professor Peter Kraft commented that the results provide an abundance of fresh information in relation to the genetic mechanisms that underlie breast cancer.
“This should provide guidance for a lot of future research,” says Kraft.
BRCA1 and BRCA2: Villainous Variants
Estrogen fuels around 7 in 10 of all breast cancers, and this subset responds well to hormone treatments like tamoxifen. The remainder are estrogen-receptor negative and are much more problematic to treat. Both types are distinct biologically and develop differently.
Some of the most notoriously dangerous genetic variations for breast cancer are BRCA1 and BRCA2. It is estimated that around 72% of women with a BRCA1 mutation and 69% of women with a BRCA2 mutation will develop breast cancer by their 80s. HER2 is another well-known gene in this regard.
Typically, however, individual variants don’t pose nearly as much of a risk as these three, though their potential adds up when combined. Lifestyle factors – alcohol, smoking, diet and more – also play a significant role in the chances of a diagnosis.
“Using data from genomic studies, combined with information on other known risk factors, will allow better breast cancer risk assessment, therefore helping to identify a small but meaningful proportion of women at high risk of breast cancer,” says co-author Jacques Simard, a professor of molecular medicine at Laval University.
“These women may benefit from more intensive screening, starting at a younger age, or using more sensitive screening techniques, allowing early detection and prevention of the disease.”