Neoadjuvant treatment with anastrozole [Arimidex] reduces the need for mastectomy in postmenopausal women with operable hormone receptor-positive breast cancer, compared with tamoxifen, according to results from the IMPACT1 study presented at the 26th annual San Antonio Breast Cancer Symposium (SABCS) [San Antonio, US; December 2003]. After 3 months, women treated with anastrozole were twice as likely as those treated with tamoxifen to have their tumour downstaged, allowing breast-conserving surgery to be performed. Combination therapy with anastrozole plus tamoxifen demonstrated efficacy similar to that of tamoxifen alone. There were no significant differences between the three treatment groups with respect to objective response rates, although a trend favouring anastrozole was observed among patients with HER2+ cancers.