Study Population: 78 patients with breast cancer metastatic to the brain (39 women whose tumors are HER2-(-) and 39 women whose tumors are HER2-(+)) to compare with published microarray studies of non-metastatic breast cancer patients with these tumor types as well as with one another to help explain the differential trend toward metastasis in patients treated with Herceptin, a new therapy directed at HER-2 over-expressing tumors.