Jewish breast cancer campaigners have hailed as “excellent” new NHS guidelines allowing potential sufferers access to drugs that reduce the risk of developing the disease.

The National Institute for Health and Care Excellence (Nice) issued a report this week saying that half a million British women should be offered tamoxifen or raloxifene which bring down the risk of breast cancer by 30 to 40 per cent.

The guidelines also modify the threshold for genetic testing, making it available to more women.

Jewish Genetics Disorder UK executive director Katrina Sarig said: “This is an excellent development. It is particularly important for Jewish people given their increased risk.”

According to the organisation, one in 40 women of Ashkenazi ancestry carry a mutation of the BRCA gene which causes breast cancer. The figure is one in 500 carriers in the general population.

Campaigner Emma Parlons, who had a preventative double mastectomy and ovary removal surgery, described Nice’s report as “a glimpse of the future”.

She said: “When my surgeon told me to stop worrying about my daughter because there will probably be a drug that she can take, she was kind of right, and it’s really exciting.”

But the 41-year-old writer was doubtful whether drugs would have sufficiently lowered her 85 per cent risk of developing breast cancer.

She said: “If I was faced with the decision today, I would still have a double mastectomy.”

Under the guidelines, women will be chosen on a case by case basis depending on family history and level of risk, which is heightened if more than one family member has suffered from cancer at a young age.

Baroness Delyth Morgan, chief executive of Breast Cancer Campaign, said: “This is a truly historic moment… we are witnessing a fundamental change of clinical practice driven by medical research.”

NICE is the first European body to recommend that healthy women be given drugs to prevent breast cancer. Concerns have been raised about potential side effects.

Katherine Woods, research information manager at the Breast Cancer Campaign, said some women may experience “menopausal-like effects” and, in very rare cases, more severe medical problems.

The issue of breast cancer screening hit the headlines earlier this year when Hollywood actress Angelina Jolie announced she had undergone a preventative double mastectomy after being diagnosed with a mutation of the BRCA gene.