Results from a major trial have shown that taking the drug anastrozole for five years can reduce the chances of high-risk women going on to develop breast cancer by 53%.
Funded by Cancer Research UK, almost 4000 post-menopausal women at high-risk of the cancer were involved.
In Scotland, it was co-ordinated at Ninewells Hospital, Dundee, the Western General Hospital in Glasgow and the Western Infirmary in Glasgow.
Professor Alastair Thompson, a researcher on the trial who is based at the Dundee Cancer Centre, said: "This opens up further possibilities for the prevention of breast cancer in postmenopausal women
"The challenge for us now is how best to implement this new knowledge into clinical practice."
Trial leader Professor Jack Cuzick said: "Our priority is ensuring that as many women as possible can benefit from these new findings."