GENES PUT 1 IN 5 AT RISK OF BREAST CANCER
Cambridge studies find 179 genetic faults which significantly raise danger to women
ONE in five women are at a significantly higher risk of breast cancer because of faulty genes, research reveals today.
Most women know that if their mother, daughter or sister has the disease, then their chances of a diagnosis are increased.
But one of the largest genetic investigations ever done for breast cancer has found 179 separate mutations which can be passed on through families. For one in five women, the errors in their genes mean they have almost a third higher chance of getting breast cancer, according to the Cambridge-led research.
For one in ten, the increased risk is as much as 70 per cent. An
unlucky 1 per cent have three times the risk of the other 99 per cent.
Scientists believe the findings could be used to save lives, as a simple blood test could identify women at a greater risk due to their genes. They could then be screened earlier or more regularly. Currently, women aged 50-70 are invited for screening every three years on the NHS.
The landmark research, across two studies, was conducted by an international team of hundreds of scientists led by Cambridge University, and analysed the DNA from 275,000 women.
The teams found almost double the number of genetic variants previously known to cause breast cancer.
Baroness Delyth Morgan, of charity Breast Cancer Now, said: ‘This is an exciting step forward … These gene changes have the potential to be incorporated into existing models to more accurately predict an individual’s risk, and to improve both prevention and early detection of the disease.’
The scientists looked at 11.8million genetic ‘spelling mistakes’ in women’s DNA which raise breast cancer risk.
They found nine variations affecting the BRCA1 gene that led to actress Angelina Jolie having a mastectomy. The star decided to undergo the procedure after learning that she carried the gene that had caused her mother to die from the disease.
In total, the two studies, published in the journals Nature and Nature Genetics, confirmed the existence of 107 genetic variants linked to breast cancer and discovered 72 new ones. They calculated that one in five women have a 30 per cent higher risk.
For the average woman, the lifetime odds of getting breast cancer are one in nine. Increasing this risk by 30 per cent means the odds would be one in seven.
Last year Chief Medical Officer Dame Sally Davies used her annual report to talk about ‘risk-based’ screening for the cancer. The research, which used chips costing less than £50 to test women’s breast cancer risk from their blood, could bring this closer to reality.
Professor Doug Easton, one of the lead investigators from Cambridge University, said: ‘We have known for a long time that breast cancer runs in families and has a substantial genetic component.
‘But judging someone’s risk based on their family is a blunt tool. This provides the exact genes which are important, and the way they will be expressed. It means some women could be offered more precise screening … or in future they might be offered preventative drugs.’
Breast cancer is the most common type in women, making up 53 per cent of diagnoses in Britain. More than 55,000 women a year are diagnosed, and around 11,000 a year die from it.
The scientists say the gene variants found, combined with ones already known, explain 39 per cent of the breast cancer risk for women whose mother, sister or daughter has had the disease.
The nine variations affecting BRCA1 offer hope for women who are told their risk of breast cancer jumps by 70 per cent on average if they carry the gene.
The scientists found the increase could be only 35 per cent for some, depending on their type of BRCA1 mutation.
Around 70 per cent of all breast cancers are fuelled by oestrogen and respond to hormone thera- pies. Others, known as oestrogen-receptor negative, are not affected by the hormone and are more difficult to treat.
The second study found ten new variants linked to these cancers – three of which were also found by the first study. Professor Jacques Simard, of Laval University in Quebec, who worked on the research, said it would help ‘identify a small but meaningful proportion of women at high risk … allowing early detection and prevention’.
Professor Shirley Hodgson, of St George’s, University of London, said that aside from strongly predisposing genes such as BRCA1, each of the variants ‘has only a small effect on breast cancer risk, but cumulatively they could be very important in altering a woman’s risk’.