A previous clinical trial found that tamoxifen, taken for five years, reduced the risk of developing invasive breast cancer by about 50% in post-menopausal women who were at increased risk of getting the disease.
Another trial found that five years of raloxifene reduces breast cancer risk in such women by about 38%.
Under the new plans, high risk post-menopausal women could be offered the drugs for a period of five years unless they have a history of thromboembolic disease or endometrial cancer.
More top news
After a mild and quiet night, the best of the sunshine will be across the south east.
The presumptive Democratic Presidential candidate said Kaine is everything Donald Trump is not as they shared a platform for the first time.
Team Sky's Chris Froome is set to win the 2016 Tour de France with an overall lead of four minutes 11 seconds after stage 20 to Morzine