They have found that older women who have high levels of particular sex hormones are up to twice as likely to develop the disease as those with low levels.
Breast cancer kills 12,000 people a year in Britain and most diagnoses are in women over 50.
The scientists found that the women most at risk were those with high levels of oestradiol, which is the main form of oestrogen, testosterone, and a hormone produced by the adrenal gland called DHEAS.
The test could be used alongside other factors including family history to identify those at high risk, they suggested. Such women could receive extra screening to check for early stage cancer, or preventive treatment.
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The researchers, from Harvard Medical School and the Brigham and Women’s Hospital in Boston, in the United States, came to their conclusions after looking back at the health of almost 800 women diagnosed with breast cancer between 1989 and 2002.
All had been through the menopause by the time the tracking study began in 1989.
The volunteers, part of the Nurses Health Study, had all agreed to have their blood taken and analysed at the start and the end of the two-decade project.
The researchers also looked at hormone levels in almost 1,600 women from the same group of nurses, who did not develop breast cancer.
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They discovered that women in the top 25 per cent of levels for the three hormones were between 50 and 107 per cent more likely to have developed breast cancer than those who were in the bottom 25 per cent.
Dr Xuehong Zhang, an epidemiologist, said that the findings suggested that looking at hormone levels could “substantially improve our ability to identify high-risk women who would benefit from enhanced screening or chemoprevention”.
The team also discovered that having higher levels of the three hormones was linked to having more aggressive breast cancer, which either recurred or caused death.
In addition, they found that particular individual hormones were closely linked to particular types of breast cancer.
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Women with higher levels of oestradiol were prone to hormone-receptor positive breast cancer, as were those with high testosterone levels.
Henry Scowcroft, science information manager at Cancer Research UK, said: “This intriguing conference report suggests that a simple one-off blood test could spot women at higher than average risk of breast cancer.
“It will be interesting to see the full results of the study when they’re finally published, but there’s a long way to go, and many questions to answer, before this could be used routinely in the NHS.”
More from the Telegraph.