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

Purpose The Immediate Preoperative Anastrozole, Tamoxifen, or Combined With Tamoxifen (IMPACT) trial was designed to test the hypothesis that the clinical and/or biologic effects of neoadjuvant tamoxifen compared with anastrozole and with the combination of tamoxifen and anastrozole before surgery in postmenopausal women with estrogen receptor (ER) –positive, invasive, nonmetastatic breast cancer might predict for outcome in the Arimidex, Tamoxifen Alone or in Combination (ATAC) adjuvant therapy trial. Patients and Methods Postmenopausal women with ER-positive, invasive, nonmetastatic, and operable or locally advanced potentially operable breast cancer were randomly assigned to neoadjuvant tamoxifen (20 mg daily), anastrozole (1 mg daily), or a combination of tamoxifen and anastrozole for 3 months. The tumor objective response (OR) was assessed by both caliper and ultrasound. Comparisons were also made of clinical response with ultrasound response, actual and feasible surgery with feasible surgery at base...