The NHS will offer the hormone therapy anastrozole to 289,000 women deemed to be at moderate or high risk of breast cancer which could halve their risk of developing the disease.
The NHS estimates 2,000 cases would be prevented if 25% of eligible women in England take up the offer - and half of those take the drug for the recommended five years.
A new breast cancer drug, called Anastrozole, which costs just 4p a day can halve the chance of a woman getting the disease and potentially help hundreds of thousands of people