This trial is being conducted to determine the impact of whole body FDG PET-CT vs. conventional staging in the management of patients presenting with clinical Stage III breast cancer. Eligible consenting patients with ductal or mixed histology breast cancer will be randomized 1:1 to whole body FDG PET-CT or conventional staging. Eligible consenting patients with lobular only histology will be entered into a separate single arm prospective study and will undergo whole body FDG PET-CT, CT with contrast of the chest/abdomen & pelvis and a bone scan.