AstraZeneca boost on positive trials

AstraZeneca set out positive data from trials of its latest cancer drugs yesterday, as it fights to improve its share of the market for treatments of the disease. But doctors in the US declined to recommend extended uses for its promising breast cancer drug until more information is available.

The company said that Arimidex, already a treatment of advanced breast cancer in post-menopausal women, was much safer than Tamoxifen ­ currently the "gold standard" for treatment in the early stages of the disease.

Arimidex is 10 times as expensive as Tamoxifen, an AstraZeneca product that has lost patent protection, and is associated with cancer of the womb. The Arimidex data, presented to the American Society of Clinical Oncology in Florida yesterday, suggests that Arimidex users are five times less likely to develop cancer of the womb than users of Tamoxifen.

However, a panel of doctors reporting to the conference said they would continue to recommend Tamoxifen as the drug of choice for early breast cancer, since no "compelling and mature data" existed on Arimidex or similar drugs.

The company also yesterday presented data for Iressa, another cancer product due on the market next year. It said trials found Iressa could shrink tumours in people suffering from lung cancer.

Cancer is one of the main battlegrounds in AstraZeneca's fight to grow earnings as its most successful drug ever ­ the ulcer treatment, Losec ­ is threatened with competition from cheap, copycat rivals. Daily sales of Losec were £10m last year.