Research published today has found that the average amount of methylation in DNA taken from blood cells could be used to assess a person’s risk of developing the disease, with lower amounts of DNA methylation indicating an increased risk.
DNA methylation is a chemical change to the DNA molecule but not the code it contains. A simple chemical tag called a methyl group is added to the DNA at various points, which helps switch genes on and off – a normal process which occurs in most cells in the human body.
The research was led by Breast Cancer Now-funded researcher Dr James Flanagan at Imperial College London, and Prof Paolo Vineis also at Imperial and the Human Genetics Foundation in Torino, Italy. The research compared the DNA from women involved in four individual studies, including Breast Cancer Now’s Generations Study.
Beyond DNA – the study of epigenetics
This study into DNA methylation is part of a wider research area called epigenetics. Genetics is the study of genes and the DNA code, but epigenetics – roughly translated as ‘on top of genetics’ – is the study of changes to our DNA that do not involve changes to the underlying code.
Epigenetics is an exciting field in science and an important area for breast cancer research.
Firstly, epigenetic changes could provide another layer of information to what we can currently learn from a person’s genes, and so help to provide a more accurate picture of someone’s chances of developing the disease. This could help find people who might qualify for risk-reducing measures such as chemoprevention or prophylactic mastectomy that would have otherwise not been identified.
A second aspect of epigenetics is that epigenetic changes are modifiable – environmental, hormonal and lifestyle factors may change epigenetic patterns like DNA methylation. Therefore we could use epigenetic changes to help monitor how a person’s risk changes over time – which could be used to test whether risk-reducing measures are really having the desired effect.
Yet another ‘simple blood test’?
DNA methylation occurs in the majority of cells in the body, but the study published today has been specifically looking at changes in white blood cells, obtained by taking a blood sample – a cheap, easy, and reliable method to study a person’s DNA. We’ve heard a lot in the news recently about ‘simple blood tests’ that claim to predict who will get cancer, which on closer scrutiny don’t always live up to the hype. So what about this research – could there be yet another simple blood test on the horizon?
The short answer is ‘not yet’. Whilst this study has confirmed that measuring DNA methylation could help predict breast cancer risk, there is still a lot of work left to do to make it into a helpful test ready for regular use in the clinic.
This study has been looking at the amount of methylation across the entirety of the DNA found in participants’ white blood cells. One of the next steps is to understand whether there is a pattern to where DNA methylation occurs. Although it could be possible to develop a test that looks at DNA methylation across the whole genome, focusing on changes in a few key areas would make such a test a lot easier and cheaper to perform. Dr Flanagan himself has already made some progress, by finding that DNA methylation on a gene called ATM can help predict a woman’s breast cancer risk.
Finding where key areas of DNA methylation occur will also help to answer why this affects breast cancer risk – what is happening differently in a cell when ‘gene X’ is or isn’t methylated, and why does that affect someone’s risk of breast cancer? Knowing the answers to these questions could help develop new methods to lower a person’s chances of developing the disease.
Bringing it all together
But perhaps the most important question to answer about DNA methylation and other epigenetic changes is how they fit into the wider picture of breast cancer risk.
We know that epigenetics won’t on its own replace how we calculate risk using genetic, environmental, and lifestyle factors, but it is yet to be confirmed how important it will be – or, to put it another way, how valuable any ‘simple blood test’ for DNA methylation will be, compared to other risk factors.
Data from research like Breast Cancer Now’s Generations Study will help us address this issue. The Generations Study provided the largest contribution of blood samples to the current study – over 1,000 of the 2,600 samples used. Being the world’s largest investigation of its kind into the causes of breast cancer, the Generations Study has already contributed a great deal to our understanding of many different risk factors, which, combined with other information, will ultimately provide women with a much more accurate picture of their own risk.
There’s been a real momentum building with research into epigenetics, and it feels like we’re on the brink of a significant change in our understanding of epigenetics and breast cancer risk. By funding researchers like Dr Flanagan and initiatives like the Generations Study we believe we can make this a reality.