Arimidex Study

AstraZeneca PLC
08 December 2004

   NEW DATA ESTABLISH ASTRAZENECA'S ARIMIDEX(TM) (ANASTROZOLE) AS SUPERIOR TO
                    TAMOXIFEN IN PREVENTING CANCER RECURRENCE


New data, from the landmark ATAC ('Arimidex', Tamoxifen, Alone or in
Combination) trial, is presented today at the San Antonio Breast Cancer
Symposium, USA.   These definitive data show that 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.  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.



'Arimidex' is the only drug of its type to have extensive safety data with over
five years of clinical experience in early breast cancer. Tolerability is of
primary concern for women with early breast cancer and for clinicians treating
them. 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. However, the side effects of '
Arimidex' are considered more predictable and manageable than some of the
serious side effects commonly associated with tamoxifen. Additionally, as a
result of the better tolerability profile, women on 'Arimidex' were more likely
to stay on therapy for longer than those on tamoxifen.



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 ATAC trial is the largest and longest running early breast cancer treatment
study. The trial reports data from over 9,300 postmenopausal women with early
breast cancer who took either anastrozole or tamoxifen once per day for five
years following their initial breast cancer surgery. This latest analysis
compares the two groups of women once the majority had completed their
treatment. The new data show that anastrozole reduces the risk of all forms of
breast cancer recurrence by an additional 26 per cent over and above that
offered by tamoxifen.  Furthermore, anastrozole provides an additional 16 per
cent reduction in the risk of the disease spreading to other parts of the body,
compared to tamoxifen.



The ATAC trial compares five years of treatment with tamoxifen to five years of
treatment with anastrozole, in women newly diagnosed with early breast cancer.
84 per cent of patients in the trial had tumours which are known to respond to
hormonal treatment.



'Arimidex' continues to grow strongly and 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).



AstraZeneca is a major international healthcare business engaged in the
research, development, manufacture and marketing of prescription pharmaceuticals
and the supply of healthcare services. It is one of the world's leading
pharmaceutical companies with healthcare sales of over $18.8 billion and leading
positions in sales of gastrointestinal, oncology, cardiovascular, neuroscience
and respiratory products. AstraZeneca is listed in the Dow Jones Sustainability
Index (Global) as well as the FTSE4Good Index.



                                     -Ends-

8 December 2004







Media Enquiries:
Edel McCaffrey, Tel: [phone]
Steve Brown, Tel: [phone]



Investor Enquiries:
Mina Blair, Tel: [phone]
Jonathan Hunt, Tel:  [phone]


                      This information is provided by RNS
            The company news service from the London Stock Exchange                   FE