Radiation Therapy to the Head in Preventing Brain Metastases in Women Receiving Trastuzumab and Chemotherapy for Metastatic or Locally Advanced Breast Cancer

OBJECTIVES: * To test if prophylactic cranial radiotherapy delivering 30 Gy in 10 fractions will significantly reduce (from 35% to 21% at 2 years) the incidence of symptomatic brain metastases in patients treated with trastuzumab (Herceptin®) for metastatic breast cancer. OUTLINE: This is a multicenter study. Patients are stratified by center, type of systemic therapy (trastuzumab \[Herceptin®\] monotherapy vs combination with chemotherapy), hormone receptor status, and presence of lung metastases (yes vs no). Patients are randomized to 1 of 2 treatment arms. * Arm I: Patients receive taxane/trastuzumab therapy for 6 weeks. While continuing taxane/trastuzumab therapy, patients then undergo 10 fractions of concurrent prophylactic cranial radiotherapy in the absence of disease progression or unacceptable toxicity. * Arm II: Patients receive taxane/trastuzumab therapy without concurrent prophylactic cranial radiotherapy. All patients undergo quality of life assessments every 8 weeks for 9 months. After completion of study treatment, patients are followed periodically for at least 1 year.