Prophylactic Cranial Irradiation in Patients With HER-2-Positive Metastatic Breast Cancer

Inclusion Criteria: * Female with HER2-positive disease * 18 years of age or older * ECOG greater or equal to 2 * Life expectancy greater or equal to 6 months * Able to complete self administered quality of life evaluations and neurocognitive testing * Willing and able to comply with study instructions and commit to all clinic visits for the duration of the study * Women of child-bearing potential must have a negative serum pregnancy test at screening and a negative urine pregnancy test at the baseline visit and must use highly effective birth control during study * Signed informed consent form Exclusion Criteria: * Current malignancy in the brain, as determined by screening MRI/CT done no more then 6 weeks prior to study treatment with PCI * Chemo or radiation planned during the period when patients will receive study treatment with PCI * Prior radiotherapy of the brain * Prior stroke or brain hemorrhage in the 6 months prior to screening * History of neurological/psychiatric disorders, including psychotic disorders or demential, or any other reason, which may affect neurocognitive assessment * Inadequate renal function * Other known previous or concomitant serious illness or medical condition that may interfere with participation in the study