Neoadjuvant Treatment of Postmenopausal Breast Cancer With Anastrozole, Tamoxifen, or Both in Combination: The Immediate Preoperative Anastrozole, Tamoxifen, or Combined With Tamoxifen (IMPACT) Multicenter Double-Blind Randomized Trial

There were no significant differences in OR in the intent-to-treat population between patients receiving tamoxifen, anastrozole, or the combination. In patients who were assessed as requiring mastectomy at baseline (n = 124), 44% of patients received breast-conserving surgery (BCS) after anastrozole compared with 31% of patients after tamoxifen (P = .23); this difference became significant for patients who were deemed feasible for BCS by their surgeon (46% v 22%, respectively; P = .03). The OR for patients with HER2-positive cancer (n = 34) was 58% for anastrozole compared with 22% for tamoxifen (P = .18). All treatments were well tolerated.

Neoadjuvant anastrozole is as effective and well tolerated as tamoxifen in ER-positive operable breast cancer in postmenopausal women, but the hypothesis that clinical outcome might predict for long-term outcome in adjuvant therapy was not fulfilled.