AstraZeneca announced today that the U.S. Food and Drug Administration (FDA) has granted full approval status to ARIMIDEX(R) (anastrozole) for the adjuvant treatment of hormone receptor-positive early breast cancer (EBC) in postmenopausal women. ARIMIDEX is the only aromatase inhibitor with study results representing a full five years of efficacy and safety data in this primary adjuvant setting, and is now the only aromatase inhibitor that has proven superior disease-free survival over tamoxifen in the primary adjuvant setting.

This long-term data for ARIMIDEX provides clinicians and patients an opportunity to make the most informed decision about their primary adjuvant therapy. "We're proud to provide doctors and patients with this critical, long-term information regarding ARIMIDEX. The five-year profile of safety and efficacy is similar to that seen in the initial analysis with no new concerns arising from this mature data set," said Joseph Purvis MD, Executive Director Medical Science at AstraZeneca. ARIMIDEX is currently the most widely prescribed aromatase inhibitor for breast cancer patients.

In September 2002, the FDA approved a supplemental New Drug Application (sNDA) for ARIMIDEX under the provisions for accelerated approval, with further follow-up required for full approval. The supplemental approval was based on recurrence-free survival data from the Arimidex Tamoxifen Alone or in Combination (ATAC) trial with a median duration treatment of 31 months.

Since that time, AstraZeneca has been dedicated to completing the commitments required by the FDA for full approval. Complete five-year data from the ATAC trial was published in December 2004 in the Lancet and was presented at the 2004 San Antonio Breast Cancer Symposium. The data indicated that ARIMIDEX significantly reduced the relative risk of breast cancer recurrence by 17 % over tamoxifen in the clinically relevant hormone receptor-positive patients for whom ARIMIDEX is indicated. This data was submitted to the FDA to satisfy the accelerated approval requirement for five years of follow-up on ARIMIDEX use in early breast cancer.

The ATAC trial is one of the world's largest breast cancer treatment studies. It also remains one of the longest running trials studying treatment after surgery for early breast cancer.

ARIMIDEX and tamoxifen remain the only hormonal therapies approved by the FDA for the primary adjuvant treatment (treatment following surgery, with or without radiation) for hormone receptor-positive postmenopausal women with early breast cancer. About ARIMIDEX(R)

ARIMIDEX is indicated for adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer.

Important Safety Information About ARIMIDEX:

ARIMIDEX should only be used in postmenopausal women. ARIMIDEX can cause fetal harm when administered to a pregnant woman. Before starting treatment, pregnancy must be excluded (see WARNINGS in full prescribing information). The most common side effects seen with ARIMIDEX versus tamoxifen in the early breast cancer clinical trial include hot flashes (36% vs 41%), joint disorders, including arthritis, arthrosis and arthralgia (36% vs 29%), weakness (19% vs 18%), mood changes (19% vs 18%), pain (17% vs 16 %), nausea and vomiting (13% vs 12%), sore throat (14% vs 14%), depression (13% vs 12%), hypertension (13% vs 11%), osteoporosis (11% vs 7%) and headache (10% vs 8%). Fractures, including spine, hip and wrist fractures, occurred more often with ARIMIDEX than tamoxifen (10% vs 7%).

Tamoxifen should not be administered with ARIMIDEX. Estrogen-containing therapies should not be used with ARIMIDEX as they may diminish its pharmacologic action.

Important Information About Tamoxifen:

NOLVADEX(R) (tamoxifen citrate) is approved for the adjuvant treatment of node-positive and node- negative early breast cancer in postmenopausal women following breast surgery and radiation. In some NOLVADEX adjuvant studies, most of the benefit to date has been in the subgroup with four or more positive axillary nodes.

Important Safety Information About Tamoxifen:

WARNING: Serious and life-threatening events associated with NOLVADEX(R) (tamoxifen citrate) include cancer of the uterus, stroke and blood clots, some of which have been fatal. In clinical trials, uterine cancers, including endometrial cancer and uterine sarcomas, and blood clots, including clots in the lungs, occurred 2 to 4 times more often with NOLVADEX than placebo, but each occurred in less than 1% of women. For most women with breast cancer, the benefits of NOLVADEX outweigh its risks. If you are taking NOLVADEX to reduce your risk of developing breast cancer because you are at high risk or have DCIS, you should discuss these warnings with your healthcare provider.

Please see Package Insert including boxed WARNING regarding NOLVADEX(R) (tamoxifen citrate) Tablets.

Women who are pregnant or who plan to become pregnant should not take NOLVADEX. Women who have a history of blood clots or who currently use anticoagulants (blood thinners) should not take NOLVADEX for DCIS or to reduce their risk of breast cancer. Cataracts and cataract surgery occurred more frequently with NOLVADEX. The most frequently reported adverse reactions were hot flashes and vaginal discharge.

ARIMIDEX and tamoxifen were developed and are distributed by AstraZeneca (NYSE:AZN), 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 $21.4 billion and leading positions in sales of gastrointestinal, cardiovascular, respiratory, oncology and neuroscience products. In the United States, AstraZeneca is a $9.6 billion healthcare business with more than 12,000 employees. AstraZeneca is listed in the Dow Jones Sustainability Index (Global) as well as the FTSE4Good Index.

For further information about AstraZeneca and full Prescribing Information please visit http://www.astrazeneca-us.com or http://www.arimidex.com.

This press release contains forward-looking statements with respect to AstraZeneca's business. By their nature, forward-looking statements and forecasts involve risks and uncertainties because they relate to events and depend on circumstances that will occur in the future. There are a number of factors that could cause actual results and developments to differ materially. For a discussion of those risks and uncertainties, please see the company's Annual Report/Form 20-F for 2004.

ARIMIDEX is a registered trademark of the AstraZeneca group of companies.