This 2 part study will explore the pharmacodynamic effects of R1507 in breast cancer tumor cells in female patients with operable breast cancer. In the first part of the study, patients will receive a single dose of R1507, 16mg/kg iv, on day 1; pre-and post-treatment (at breast surgery on day 8) breast tissue samples will be obtained for measurement of IGF-1R expression. If sufficient biological activity is demonstrated, 3 additional cohorts of patients will be entered into Part 2 of the study, to receive a single dose of 9mg, 3mg/kg or 1mg/kg iv R1507, respectively. The anticipated time on study treatment is \< 3 months, and the target sample size is \<100 individuals.