Prof Doug Easton

Professor Doug Easton

Cancer Research UK Genetic Epidemiology Group
University of Cambridge
Cambridge

Hunting cancer susceptibility genes

Professor Douglas Easton is director of the Cancer Research UK Genetic Epidemiology Group at the University of Cambridge. He is world-renowned for his research into genes that affect our risk of common cancers, particularly breast cancer. His team also works on ovarian and prostate cancer, and melanoma. Their findings will help identify high-risk individuals and could lead to new ways of preventing, diagnosing and treating the disease in the future.

Breast cancer genetics

A person's genes play an important role in determining how likely they are to develop cancer. Scientists have been trying to understand exactly which genes are involved, and how much of an effect they have on a person's risk.

In the 1990s, Professor Easton's team helped track down two genes, BRCA1 and BRCA2, which strongly influence breast cancer risk. Evidence suggests that inheriting a faulty copy of either of these 'high-risk' genes is for around 5 per cent of breast cancers overall.

However, around 4 out of 5 families with multiple cases of breast cancer do not have a faulty copy of either BRCA1 or BRCA2. Professor Easton suspects there are many more breast cancer genes, each with a much weaker effect. A woman would need to inherit several of these 'low-risk' genes to significantly increase her lifetime risk of breast cancer.

To track down these other genes, Professor Easton's team is running a large study comparing DNA samples from thousands of breast cancer patients with those taken from healthy people. They aim to pinpoint subtle genetic variations found more often in samples from patients, as these may influence cancer risk.

This ground-breaking study has already yielded promising results. Professor Easton's team and their collaborators have uncovered five regions of DNA, each of which contains genes that affect a woman's risk of breast cancer.

But the combined effect of all the breast cancer genes discovered so far still only explains about a quarter of the 'inherited risk' that population studies of suggest exists. So there must be other genes involved, and Professor Easton and his team are continuing their efforts.

Other breast cancer risk factors

The team is currently leading a large-scale study called EMBRACE that aims to monitor more than 3,000 women, half of whom have faults in BRCA1 or BRCA2. They hope to uncover other genes, as well as lifestyle and environmental factors, that affect their likelihood of developing breast cancer.

Professor Easton is also leading a large-scale study on more than 4,000 women, looking for genes that influence other known breast cancer risk factors, such as breast density and hormone levels.

And the team has developed a computer programme called BOADICEA, which can predict an individual's risk of breast or ovarian cancer. They plan to update this when new genes, environmental or lifestyle factors are discovered. This should be a useful tool for doctors in the future to identify individuals at increased risk and help them, by referring them for counselling and regular screening if appropriate, and by providing advice about ways to lower their risk.

Most recently, Professor Easton's team successfully identified a variation in a gene called CASP8 that slightly reduces the risk of breast cancer.

Other cancers

Professor Easton is also leading other large-scale DNA studies to hunt for genes that influence our susceptibility to other common cancers, including prostate cancer and melanoma.

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