Researchers: Arimidex™ Should Replace Tamoxifen for Treating Advanced Breast Cancer

Arimidex™ (anastrozole) should now replace tamoxifen as the treatment of choice for post-menopausal women with hormone-sensitive advanced breast cancer, according to researchers reporting on the largest study to date comparing the two drugs.

The study, reported in the journal Cancer, consisted of two randomized, double blind multi-center trials. The first trial was conducted in 97 centers across North America and Canada and the second study was conducted in 83 sites in Europe, Australia, New Zealand, South America and South Africa.

The studies compared treatment with Arimidex or tamoxifen in post-menopausal women with hormone-sensitive or receptor-unknown tumors.

Researchers found Arimidex significantly superior to tamoxifen in terms of average time to disease progression, with the average time using Arimidex at 10.7 months and an average time of 6.4 months with tamoxifen.

Researchers believe that the benefits of Arimidex over tamoxifen may have been diluted by the high proportion of patients with tumors of unknown hormone receptor status who took part in the research.

Both drugs were generally well tolerated and appeared similar in terms of side effects reported. However, a significantly lower incidence of thromboembolic events were seen in patients receiving Arimidex compared with those taking tamoxifen, researchers reported. Patients taking Arimidex also had a lower incidence of vaginal bleeding than the tamoxifen users.

"In post-menopausal women with hormonally-sensitive breast cancer, anastrozole should be considered as the new standard first-line treatment," concluded the researchers.

"The optimum balance of the efficacy and tolerability data confirm that Arimidex should be considered as a new standard first-line treatment for post-menopausal women with hormonally-sensitive breast cancer," said Jacques Bonneterre, Professor of Medical Oncology at Centre Oscar Lambret in France and lead investigator.

"Arimidex was shown to be more effacious than tamoxifen in patients with hormone-sensitive disease, who are the most appropriate group of patients for hormonal therapy in advanced breast cancer."

Further research is underway to see if the benefits of Arimidex also apply to the treatment of early breast cancer.

Other Sources: AstraZeneca