Studies suggest the drug could protect women against breast cancer

Researchers at Cancer Research UK will test Anastrozole on 10,000 women across the world over the next 10 years.

They believe the drug, which is an effective treatment for breast cancer, could also have a protective role.

They believe it could reduce the risk of breast cancer in post-menopausal women by more than 50%, potentially saving thousands of lives.

Promising results

The study follows a trial, which looked at how effective Anastrozole is at treating early breast cancer.

During that trial, researchers noticed that women who took the drug were around 40% less likely to be diagnosed with a second cancer in the opposite breast compared to women taking a drug called tamoxifen.

UK trial centres Northwick Park & St Marks Hospitals, Harrow Bristol Haematology and Oncology Centre Yeovil Hospital Frenchay Breast Care Centre, Bristol Leeds General Infirmary Castle Hill Hospital, Cottingham Derby City General Hospital Queen Elizabeth hospital, Birmingham Withington Hospital, Manchester Guy's NHS Trust, London Royal Liverpool University Hospital St. James's Hospital, Leeds University of Wales College of Medicine, Cardiff Western General Hospital, Edinburgh St Margaret's Hospital, Epping Royal Cornwall Hospital, Treliske City Hospital, Nottingham Chelmsford & Essex Centre Royal South Hants Hospital, Southampton South and East Dorset Primary Care Trust, Ferndown

Tamoxifen is already known to reduce the risk of breast cancer by one third in women with a higher risk of the disease.

This has prompted the researchers to speculate that anastrozole may be even more effective.

The 10-year-study aims to provide conclusive evidence on whether or not it can protect women from breast cancer.

"The new trial has the potential to have an even more dramatic impact on the disease," said Professor Jack Cuzick of Cancer Research UK, who is leading the study.

Both anastrozole and tamoxifen work by interfering with the female hormone oestrogen, which is known to be the most important cause of breast cancer.

Tamoxifen works by preventing the action of oestrogen on the cells of the breast but maintains the beneficial effects of oestrogen on bone. Anastrozole actually prevents the production of oestrogen.

International study

The trial aims to recruit 10,000 women from 40 centres around the world, 20 of which will be in the UK. Half of these will be given anastrozole.

This will enable the doctors to compare their progress with those who are not taking the drug.

"Anastrozole looks like a very promising option but the only way we will know for sure is to carry out this large scale trial," said Kate Law, head of clinical trials at Cancer Research UK.

Delyth Morgan, chief executive of Breakthrough Breast Cancer, said: "This is welcome news for post-menopausal women who are at higher risk of developing breast cancer, in particular women with a strong family history of the disease, who account for between 5 and 10% of all breast cancer cases.

"We will be interested to see how the trial progresses, including the long-term effectiveness and side effects of the drug."

Samia al Qadhi, joint chief executive of Breast Cancer Care added: "We see this trial as a positive step for post-menopausal women in a high-risk group."

Around 30,000 postmenopausal women are diagnosed with breast cancer in the UK every year.

If half of these women could be protected from the disease, it could lead to a substantial fall in deaths.

Breast cancer risk depends on a number of factors, including age, family history, and whether or not a woman has had children.

About 77% of women with breast cancer are aged over 50 at diagnosis.

Up to 10% of breast cancer cases are thought to be hereditary.

Having a mother, sister or daughter with breast cancer can double a woman's chances of developing the disease.

Women with either of two defective genes called BRCA1 and BRCA2 are at an increased risk of both breast and ovarian cancer.

If a woman has already had breast cancer in one breast, she is three or four times more likely than average to develop the disease in the other.