By Gareth Evans, Professor of Medical Genetics and Cancer Epidemiology
This month, I presented a talk at the annual San Antonio Breast Cancer Symposium, a global gathering of the leading minds in breast cancer research which provides state-of-the-art information on breast cancer. I was speaking about one of my research projects, funded by Prevent Breast Cancer – SNPs. This piece of research, currently in its third incarnation, is specifically concerned with identifying which fragments of the DNA, called SNPs, can increase a person’s chance of getting breast cancer and how we can tailor our NHS breast screening programme to incorporate this knowledge.
As you may know, there are a number of factors that come into play to affect a person’s chance of getting breast cancer. Lifestyle factors, such as the age at which a woman had her first period or her first full-term pregnancy, have an impact – the younger, the better, is the general consensus in these cases. Body mass index, amount of exercise taken and alcohol intake also have an impact.
There’s also the matter of breast density. Having denser tissue in the breast is the largest risk factor after family history and age. Breast density is nothing to do with breast size or anything else immediately obvious – it’s only determined via a mammogram but a woman with dense breasts could expect a 25 per cent lifetime risk, compared with a four per cent lifestyle risk for a woman with low breast density.
Finally, there are genetic factors, such as a strong family history or being a carrier of the BRCA1 or BRCA2 genetic mutations. Importantly, we can now also add to this the inclusion of 200 known genetic variants that can increase the risk of breast cancer by between eight and 40 per cent – these are SNPs, and the discovery of these 200 fragments means that we can help to give women (and men!) a more accurate picture of their risk. SNPs are far more commonly found than the BRCA gene mutations, making them an incredibly important part of the picture for risk prediction.
In fact, we know that only around 20 per cent of familial breast cancer is caused by BRCA gene mutations. Our work on SNPs is showing that a further 34 per cent of hereditary breast cancer can be attributed to SNPs variations. What we’re now doing in Manchester, under our PROCAS research programme, is giving women a polygenic risk score, which is essentially a more accurate assessment of their lifetime risk of getting breast cancer.
The really important part, however, is that over the time we’ve been running SNPs and PROCAS, we’ve been able to show the feasibility of using SNPs in screening and the accuracy of doing so. So, for me, the next step is working to get SNPs mapping and assessment included as standard in family history clinics. Eventually, they should also be included for every woman presenting for mammography.
Gareth filmed a quick video discussing his work:
To donate to our current SNPs project, please visit our donate page and pick Gene Research from the drop down options.