Previously, Arimidex was only approved for use after disease progression following tamoxifen treatment. Two pivotal studies found that Arimidex was as effective and well tolerated as tamoxifen when prescribed at the time of diagnosis for women with advanced breast cancer.

Arimidex was first approved in 1996 as a treatment for post-menopausal women with advanced breast cancer who progressed following hormonal treatment with tamoxifen. Arimidex is a non-steroid aromatase inhibitor, which works to lower the amount of circulating estrogens in the body. Earlier this year, the drug gained approval in several European countries for first-line use in post-menopausal women with advanced disease.

AstraZeneca is a major international healthcare business engaged in the research, development, manufacture and marketing of ethical (prescription) pharmaceuticals and the supply of healthcare services. It is one of the top five pharmaceutical companies in the world with healthcare sales of $15 billion and leading positions in sales of gastrointestinal, oncology, anesthesia including pain management, cardiovascular, central nervous system (CNS) and respiratory products.