The National Institute for Health and Care Excellence is now backing the use of three medicines to prevent breast cancer in women with a family history of the disease, adding anastrozole to the mix for the first time.

The cost regulator is recommending that doctors prescribe either tamoxifen, raloxifene and now anastrozole to potentially hundreds of thousands of 'healthy' women who have no personal history of breast cancer but have a higher risk of developing it.

According to the draft guidelines, doctors should offer tamoxifen for five years to premenopausal women at high risk of breast cancer, unless they have a past history or may be at increased risk of thromboembolic disease or endometrial cancer, and anastrozole for five years to postmenopausal women at high risk of breast cancer unless they have severe osteoporosis.

For postmenopausal women at high risk of breast cancer with severe osteoporosis, but no history or increased risk of thromboembolic disease or endometrial cancer, tamoxifen should for offered, or raloxifene as an alternative to for women with a uterus.

Experts have welcomed the inclusion of anastrozole in the recommendations, as clinical studies have shown that the drug cut the risk of the disease in post-menopausal women by more than 50 percent in the first five years of use, but with fewer side effects than other preventive options.

According to NICE, new evidence demonstrated that if 1,000 women at high risk of breast cancer took anastrozole for five years 35 cases of breast cancer would be prevented, compared to 21 if they took tamoxifen.

"That the most effective preventive drug for post-menopausal women at high risk of breast cancer has now been recommended for routine use is fantastic news," said Baroness Delyth Morgan, chief executive of Breast Cancer Now. "However - like tamoxifen - anastrozole is not licensed for this purpose, and we are concerned that patients will therefore not be able to access this treatment, despite this recommendation."

"Ultimately, if the full potential of anastrozole is to be realised for post-menopausal women, there needs to be far greater awareness and support for GPs in prescribing off-label treatments."