First Comparison of Anastrozole vs Tamoxifen

Women treated with tamoxifen (Nolvadex) had a 13% higher risk of disease progression than those treated with anastrozole (Arimidex), according to the North American and the European Tamoxifen or Arimidex Randomized Group Efficacy and Tolerability (TARGET) study. This finding suggests that anastrozole may be a more effective treatment option for many postmenopausal women with advanced breast cancer. The results from the TARGET study were reported at the 22nd Annual San Antonio Breast Cancer Symposium.

These randomized, double-blind studies were designed to demonstrate the efficacy of anastrozole and tamoxifen treatments in postmenopausal women with advanced breast cancer. A total of 1,021 patients were included in the studies.

Aman Buzdar, MD, from The University of Texas M. D. Anderson Cancer Center said, “We know that tamoxifen and Arimidex are both effective treatments for women with advanced breast cancer. But until now, the two have never been compared directly in a clinical trial. This is the first time that we have seen an aromatase inhibitor prove to be as effective as tamoxifen.”

Anastrozole, a selective, nonsteroidal aromatase inhibitor, differs from tamoxifen because it inhibits a key step in the production of estrogen. Anastrozole is currently available in most countries, including the United States, for the treatment of advanced breast cancer in postmenopausal women following disease progression during treatment with tamoxifen or other antiestrogens. The Arimidex, Tamoxifen Alone or in Combination (ATAC) trial for adjuvant use of anastrozole is ongoing.