Anastrozole data show continued delay in relapse, but no clear survival advantage.

For the first time in 20 years, another class of drugs—aromatase inhibitors— is challenging tamoxifen as the treatment of choice for postmenopausal women with early breast cancer. However, the higher cost of at least one of the aromatase inhibitors and the lack of a statistically significant advantage in breast cancer survival give some researchers pause in wholeheartedly endorsing the drugs. Final results of the Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial, presented at this year's San Antonio Breast Cancer Symposium and published simultaneously in The Lancet, found that, compared with tamoxifen, anastrozole (Arimidex) improved disease-free survival by 13% (17% among hormone-responsive patients) and increased time to recurrence by 21% (26% in hormone-responsive patients) in postmenopausal, estrogen receptor–positive women with early breast cancer; however, there was no statistically significant improvement in breast cancer survival or overall survival. " Anastrozole is the initial treatment of choice for hormone receptor–positive early breast cancer in postmenopausal women, " concluded in his presentation in San Antonio. The ATAC trial was the first random-ized trial to test an aromatase inhibitor as first-line therapy in postmenopausal women with hormone-responsive early breast cancer. Between 1996 and 2000, more than 9,000 women were randomly assigned to receive anastrozole, tamoxifen, or a combination of the two drugs as adjuvant therapy. The combination arm of the trial was shut down early because of a lack of efficacy beyond either of the agents alone. Three aromatase inhibitors— anastrozole, letrozole (Femara), and exemestane (Aromasin)—are approved in the United States for use in women with metastatic breast cancer. Two major randomized trials in the adjuvant setting have found that women previously treated with tamoxifen who took an aromatase inhibitor had a lower risk of recurrence compared with women who continued tamoxifen or took placebo after 2 to 3 years of tamoxifen. In November, the American Society of Clinical Oncology made public its updated technology assessment of aromatase inhibitors. " Optimal adjuvant hormonal therapy for a postmenopausal woman with receptor-positive breast cancer includes an aromatase inhibitor as initial therapy or after treatment with tamoxifen, " the expert panel wrote in the assessment, which will be published this month in the Journal of Clinical Oncology. " Women with breast cancer and their physician must weigh the risks and benefits of all therapeutic options. " The latest update of ATAC, taken with results from earlier trials, shows that there is a substantial reduction in relapse rate …