Gene find could help spot breast cancer risk

Molecular changes that switch genes on or off can set the stage for breast cancer many years before the disease is diagnosed, research suggests.

The discovery could lead to a blood test that will help doctors identify women who are most at risk.

Scientists analysed blood samples from 1,380 women of various ages, 640 of whom went on to develop breast cancer.

A strong association was found between molecular modification of a white blood cell gene called ATM and breast cancer risk.

The scientists looked for evidence of a chemical effect called methylation, which acts as a “gene switch”.

Women showing the highest methylation levels affecting the ATM gene were twice as likely to develop breast cancer as those with the lowest levels.

On average, the blood tests were carried out three years before diagnosis. In some cases they pre-dated the discovery of breast cancer by up to 11 years.

The results were especially clear in blood samples from women under the age of 60.

Methylation is an “epigenetic” mechanism that allows genes to be affected by exposure to environmental factors such as hormones, radiation, alcohol, smoking or pollution.

Increasingly, epigenetic effects are being seen as important drivers of cancer.

Dr James Flanagan, of Imperial College London, who led the new research, said: “We know that genetic variation contributes to a person’s risk of disease.

“We can now also say that epigenetic variation also has a role.”