The soaring rate of breast cancer could be curbed if drugs to prevent the disease were offered to women in the same way that statins to lower cholesterol are offered to people at risk of heart disease, say experts.
One in 10 women in the highest risk band would benefit, they said.
Trials of newer drugs could eventually see preventive treatment offered to as many as half of all post-menopausal women.
The 12 international experts met in Switzerland last year to review the latest evidence and publish their conclusions in Lancet Oncology today.
They draw a parallel with statins for the prevention of heart disease.
But the use of drugs to prevent cancer is in its infancy and is still unfamiliar.
"The idea of preventing cancer with drugs seems quite alien," said Professor Jack Cuzick, the chairman of the expert panel. "But if someone came to a clinic with high cholesterol and was told 'Come back in a year and we will check you again' you would think that was mad. Yet that is what we do with cancer."
The equivalent of cholesterol levels in cancer is the density of the breast tissue, as seen on a mammogram.
Women with dense breasts have a four times greater chance of developing cancer than those with the least dense breasts.
One in 10 women has dense breasts.
The main drug recommended is tamoxifen, which shows a 40pc reduction in risk when taken for five years but has side effects including blood clots and a small extra risk of womb cancer. But a trial of a newer class of drugs, aromatase inhibitors, is under way and may show an even bigger reduction in breast cancer risk.