Study: Arimidex® Better Than Tamoxifen for Women With Early Breast Cancer

Researchers reported that data from the largest breast cancer treatment trial ever conducted showed Arimidex® (anastrozole) to be more effective than tamoxifen in reducing the risk of recurrence for postmenopausal women who had early breast cancer.

The researchers, reporting at the San Antonio Breast Cancer Symposium, said 317 of 3,125 women in a group of patients given Arimidex had a recurrence of their breast cancer or died, compared with 379 of 3,116 women given tamoxifen.

This represented a 17 percent reduction in the risk of breast cancer recurrence with Arimidex treatment over tamoxifen, according to researchers at the University of Texas M.D. Anderson Cancer Center in Houston. The reduction in the risk of recurrence was 22 percent in women with confirmed hormone-sensitivity tumors with Arimidex treatment compared to tamoxifen, according to the study.

"Now after 20 years, tamoxifen's established benefits in early breast cancer are being challenged," said Dr. Aman Buzdar, principal researcher of the study. "Tamoxifen is a very effective drug, but it has side effects, like an increased risk of endometrial cancer, that have to be managed. The goal of research in this area is to improve that profile."

Arimidex works by reducing estrogen in postmenopausal women whereas tamoxifen works by selectively blocking estrogen from stimulating breast cancer cells by binding to the estrogen receptor.

This new data is the first report from the ATAC (Arimidex, Tamoxifen Alone or in Combination) study, which is the largest breast cancer treatment trial ever conducted. The trial involves 9,366 patients from 380 cancer centers in 21 countries. Further research is planned to confirm if the observed reduction in relapse rates with Arimidex will impact long-term survival.

Other Sources: AstraZeneca