Hundreds of thousands of women at high risk of developing breast cancer in Britain should be given drugs which could dramatically reduce their chances of getting the disease, doctors were advised Tuesday.
In guidelines issued by the National Institute for Health and Care Excellence (Nice), up to half-a-million women with a family history of the illness should receive the £120 ($185, 141 euros), five-year course of tamoxifen or raloxifene.
The "one-a-day" programme is an alternative to the surgery chosen by celebrities including Angelina Jolie and Sharon Osbourne, said Nice.
Tamoxifen was shown in a clinical trial to reduce the risk of developing invasive breast cancer by about 50 percent in high-risk post-menopausal women.
Another trial found raloxifene reduced the risk by around 38 percent although neither drug is currently licensed as a preventative treatment in Britain.
"Tamoxifen is extremely cost effective, that's because it's extremely cheap... and treating someone with breast cancer costs many thousands of pounds," explained professor Gareth Evans, who helped to develop the guidelines.
"So this treatment is potentially not just cost-effective but cost saving to the NHS and more importantly for women, they don't have to go through the stress and trauma of a diagnosis, radiotherapy, potentially chemotherapy.
"So it's a major breakthrough for women that they are going to be able to be offered this treatment in the future," he added.
Breast cancer awareness campaigners praised the report.
"We believe that this guideline is a game changer for people with a family history of breast cancer," said Caitlin Palframan, assistant head of policy at Breakthrough Breast Cancer.
"In fact for breast cancer overall it's a historic step for prevention.
"We think more women will have more options to reduce their risk, which ultimately means we will prevent more breast cancer cases."
Around 50,000 women and 400 men develop breast cancer every year in Britain, according to Nice figures.
Explore further: UK considers preventative drugs for breast cancer (Update)