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Home About Us Lunenfeld-Tanenbaum Spotlight LTRI Q&A: How do we predict breast cancer risk more effectively?

LTRI Q&A: How do we predict breast cancer risk more effectively?

As researchers uncover more genetic links to breast cancer, and with women paying more attention to these and other risk factors, two LTRI scientists are part of an international team that are digging deeper into new gene variants that can put a person at increased risk for breast cancer. 
breast cancer image.jpg  


The image above is a stain of a breast tumour. The dark purple cells with large blue nuclei are the cancer cells invading into the lymphovascular blood vessels (the large white empty space). The lighter pink cells are normal breast tissue cells. Patients that are positive for lymphovascular invasion have a higher likelihood of a recurrence of the disease.


As recently reported in the journal Nature Genetics, Drs. Irene Andrulis and Julia Knight collaborated with an international group of cancer researchers, called the Breast Cancer Association Consortium, to identify 15 new gene variants that can put a person at increased risk for breast cancer.
Although the new gene variants are not as well-known as the BRCA1 or BRCA2 mutations, these new genes still pose a significant risk for breast cancer, with the potential to impact how women are screened for the disease.
In this Q&A with both Drs. Andrulis and Knight, we take a closer look at what their recent findings mean for the field of breast cancer, and why the findings are important for predicting breast cancer risk.
Q. People are familiar with the BRCA1 and BRCA 2 genes, thanks in part to celebrity Angelina Jolie, but why is it important to study these other gene variants?
A. For the BRCA 1 and BRCA2 genes, we now know what the proteins do, and what effect the mutations may have in relation to risk for breast cancer. The common variants that we studied are different because individually, they pose a very small risk. But when you group them together, they have a larger effect on a person’s risk for breast cancer. Previous studies identified 79 different common variants, which we refer to as SNPs, associated with breast cancer - with this study, we’d added 15 more, which will improve accuracy of predictions.
Q. It looks like the Breast Cancer Association Consortium studied a huge number of breast cancer cases for this large-scale meta-analysis. Can you explain why the study was set up this way?
A. The breast cancer risk associated with each individual common SNP variant is very low, compared to mutations in BRCA1 or BRCA2, so we have to use very large-scale studies with a huge cohort of patients to pool the data and study the effects of these gene variants. The data has been pooled from centres from around the world, so we’ve been able to look at DNAs from over 120,000 women.
Q. Why was this Nature Genetics study significant?
A. Previously, the international consortium that we are a part of, had already identified some gene variants that are associated with breast cancer risk, and more were identified in this study, because more women were studied and additional techniques were used for analysis. Now we also have more advanced molecular technologies, or platforms, that allow us to do that effectively.
This Nature Genetics paper also led to another study that the group just published in the Journal of the National Cancer Institute (JNCI), where we’re striving to refine the current screening model that is in use by clinicians when assessing a person’s risk for breast cancer. The model takes into account the age of the woman, her family history, and other components that we already know that are related to risk in breast cancer, but now we have added the common gene variants, these new SNPs, which we’ve uncovered. The new JNCI paper also shows how at different ages you can use these SNPs to better predict risk. For example, screening may be more effective for a particular individual in her 40s, compared to someone else of the same age but with a different risk profile. We will be able to better tailor screening and prevention for women based on their risk assessment. 
Q. What are you working on next?
A. The idea is to continue to identify gene variants that will give the best predictor of cancer risk. The predictor of risk for cancer is not only based on these SNPs, but will also take into account other cancer susceptibility genes (such as BRCA 1, BRCA2 and intermediate risk breast cancer susceptibility genes), as well as other factors like breast density, lifestyle, etc. to give us an overall risk assessment for a person.
Currently, Dr. Andrulis is part of a team, led by Drs. Jacques Simard and Bartha Knoppers from Quebec, who are trying to figure out how to move all of this information from the research laboratory into shaping health policy. This effort is funded by a grant from Genome Canada. An example of this would be improving guidelines for breast cancer screening. The goal is to try to give women a better idea of their risk and to determine how often women should be going for screening. This is where the research is leading.



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