Thousands of women with a family history of breast cancer could be offered a cheap drug to reduce their risk of getting the disease themselves.
A new draft guideline from the National Institute for Health and Care Excellence (Nice) says GPs should consider offering anastrozole to post-menopausal women who are deemed to have a "high" or "moderate" risk of breast cancer.
It is estimated that around one in 10 women over the age of 50 have a higher risk of getting the disease - some 600,000 around the UK.
The drug, which costs £1.19 for 28 tablets, has been shown to be "effective for the primary prevention of breast cancer", according to Nice's consultation document.
The health watchdog said the drug should be offered to women with an increased risk of breast cancer for five years unless they have severe osteoporosis.
Its draft guideline states that for women at high or moderate risk of the disease, anastrozole results in considerably fewer breast cancer cases and lower costs than the drugs tamoxifen and raloxifene.
Nice estimates that if 1,000 high-risk women took anastrozole for five years, 35 breast cancer cases would be prevented.
And for every 1,000 moderate-risk women who took the drug for five years, 27 cases could be prevented.
Nicola Smith, senior health information officer at Cancer Research UK, told the Daily Mail: "Taking a pill to reduce the risk of breast cancer is an encouraging new option for post-menopausal women at high risk of the disease.
"For most women, the side-effects of anastrozole are likely to be less severe than those experienced with tamoxifen which also reduces breast cancer risk.
"It's important for women to consult their doctor if they think they might be at high risk of breast cancer."
Professor Mark Baker, director of the centre for guidelines at Nice, told the newspaper: "The evidence examined by the committee suggests anastrozole will not only reduce the number of breast cancer cases in these women compared with tamoxifen, but it is also a more cost-effective option."