Genetic test could help identify breast cancer risk

In collaboration with the Press Association

UK researchers have taken a step towards identifying women at increased risk of breast cancer by analysing their DNA.

“This study shows how the genetic map of breast cancer might be used to identify women most at risk" - Nell Barrie, Cancer Research UK

The findings suggest that developing a test for a group of DNA changes could one day help doctors detect those with an increased risk of the disease. 

Improving the accuracy of risk analysis in this way could help tailor screening in the future, and serve as a guide for information and support given to women.

The team, led by scientists at the Institute of Cancer Research and the University of Cambridge, analysed 77 individual DNA changes that have been linked with slight increases in breast cancer risk on their own. 

But the increased risk is smaller than for other genetic faults, such as inherited changes in the BRCA1 and BRCA2 genes that can increase a woman’s risk of breast cancer by up to 90 per cent.

Studying data from 65,000 women, the researchers came up with a measure of risk – called a ‘polygenic risk score’ – based on the appearance of faults in these 77 regions.

Using one of the world’s biggest databases of genetic information – called the Collaborative Oncological Gene-Environment Study – they found a link between higher ‘polygenic risk scores’ and a woman’s risk of breast cancer.

But experts warn that further analysis is needed to determine how best to use these genetic markers.  

Nell Barrie, senior science communications manager at Cancer Research UK - which part funded the study – said: “This study shows how the genetic map of breast cancer that scientists have been building up over the years might be used to identify women most at risk, so we can take steps to reduce their chances of developing the disease or catch it at the earliest possible stage.”

A woman in the top 20 per cent for polygenic risk score was 1.8 times more likely to develop breast cancer than the average woman. A woman in the top 1 per cent, on the other hand, was more than three times more likely to develop breast cancer. 

Risk for women with a history of breast cancer in their close family was 24.4 per cent if they were in the highest-scoring fifth. In comparison, it was 8.6 per cent if they were in the lowest fifth.

For women without a history of breast cancer in their close family, the risks were 16.6 and 5.2 per cent respectively.

Study co-leader Professor Douglas Easton, director of the Centre for Cancer Genetic Epidemiology at the University of Cambridge, said: “There’s still work to be done to determine how tests like this could complement other risk factors, such as age, lifestyle and family history,” he said. 

“But it’s a major step in the right direction that will hopefully see genetic risk prediction become part of routine breast screening in the years to come.”

The study is published in the Journal of the National Cancer Institute.  

References

  • Mavaddat, N., et al. (2015). Prediction of Breast Cancer Risk Based on Profiling With Common Genetic Variants JNCI Journal of the National Cancer Institute, 107 (5) DOI: 10.1093/jnci/djv036