In postmenopausal women with hormone sensitive, early breast cancer, AstraZeneca's treatment, 'Arimidex' (anastrozole), reduces the risk of breast cancer returning by an additional 26 per cent over and above the 50 per cent reduction in risk already offered by tamoxifen, according to a new data, from the landmark ATAC ('Arimidex', Tamoxifen, Alone or in Combination) trial, presented at the San Antonio Breast Cancer Symposium, USA.

These data also conclude that 'Arimidex' is associated with fewer life threatening side effects than those seen with tamoxifen, particularly blood clots, stroke and cancer of the womb lining.

The greatest fear for women who have been treated for early stage breast cancer is to have their cancer return. Experts agree that the first five years following primary surgery is when women are at greatest risk of their disease returning.

Data from the ATAC trial now conclusively demonstrate that 'Arimidex' provides women with even greater protection than tamoxifen by reducing the risk of breast cancer recurrence by over half as much again. As a result, more women can live cancer free. A reduction in this risk of recurrence is associated with an improvement in overall survival; 'Arimidex' offers women the best possible chance to stay alive and cancer free, release from AstraZeneca said here.

"It is critical that women get the best treatment option available to them at the earliest opportunity after diagnosis to minimise the risk of recurrence," said Professor John Forbes of Newcastle Mater Misericordiae Hospital, Australia.

John Forbes added, "Quite simply, if breast cancer does not return, women will not die from it. With tamoxifen, many women have had to live with the risk that their breast cancer could come back, even before they have completed their course of treatment. Now, for the first time in 30 years, we have a drug that is better than tamoxifen to fight breast cancer - anastrozole."

'Arimidex' is the only drug of its type to have extensive safety data with over five years of clinical experience in early breast cancer. These data show that 'Arimidex' is better tolerated than tamoxifen, both for serious life threatening side effects and other side effects affecting quality of life. Women taking 'Arimidex' in the ATAC trial experienced more fractures and joint pain than those receiving tamoxifen, which is known to have a positive effect on bone mineral density.

The vast majority of patients in the ATAC trial have completed five years of treatment and these data are now considered conclusive. Breast cancer specialists believe that anastrozole should replace tamoxifen as the preferred initial hormonal treatment, in order to provide women with the best possible chance of staying free of their disease, the release added.

'Arimidex,' in the first nine months of 2004, had sales of $578 million, an increase of 45 per cent on the same period last year (2003).