These are initial results from ATAC (Arimidex, Tamoxifen, Alone or in Combination) Trial, the biggest breast cancer study that started in the United Kingdom in 1996, the results of which were presented recently at the San Antonio Breast Cancer Conference in the United States.
This is the first time that the benefits of tamoxifen have been surpassed by another treatment in this setting, and marks an important breakthrough in the management of this devastating disease.
Arimidex (anastrozole), which works in a different way to tamoxifen by stopping estrogen production in postmenopausal women, is currently available for the treatment of advanced breast cancer.
When approved for use in early breast cancer, Arimidex (anastrozole) will provide clinicians and patients with a new treatment option.
The ATAC Trial is an international study of over 9,300 postmenopausal women with early breast cancer. There are 381 centers worldwide involved in the study. The trial hopes to find in five years whether Arimidex (anastrozole) is as effective as and safer than tamoxifen or if the combination of Arimidex (anastrozole) and tamoxifen would offer additional benefits for breast cancer patients over tamoxifen alone.
The investigators found that when the treatments were given on their own, Arimidex (anastrozole) was more effective than tamoxifen in prolonging disease-free survival. This means that it was more likely to prevent the cancer from recurring, not only in the same breast, but also in the other breast and elsewhere in the body.
In addition, there was a lower incidence of some important side-effects in the Arimidex (anastrozole) group compared with the tamoxifen-treated group.