The investigators propose to conduct a Phase I/randomized Phase II study design in order to test the tolerability and efficacy of AZD0530 when used together with anastrozole in therapy for ER+ and/or PR+, postmenopausal breast cancer. The Phase I pharmacokinetic (PK) cohort of the study (cohort A) in postmenopausal women with metastatic breast cancer 2008-2009 showed initial safety,tolerability and good bioavailability of both drugs and determined the doses for use in the ongoing Phase II trial. In the randomized Phase II cohort of the study (cohort B), postmenopausal women with newly diagnosed, previously untreated ER+, HER2 negative breast cancer that is at least 2 cm or more in diameter by clinical exam or radiology will be randomized to either neoadjuvant treatment with anastrozole plus placebo, or anastrozole in combination with AZD0530. The Phase II cohort will permit extended assays of tolerability, initial estimates of efficacy, and the investigation of molecular predictors of drug efficacy.