Testing Longer Duration Radiation Therapy Versus the Usual Radiation Therapy in Patients With Cancer That Has Spread to the Brain

PRIMARY OBJECTIVE: I. To determine if the time to local failure is improved with FSRS compared to SRS in patients with intact (i.e., unresected) brain metastases. SECONDARY OBJECTIVES: I. To compare time to intracranial progression-free survival between FSRS and SRS. II. To compare overall survival between FSRS and SRS. III. To determine if the time to local failure is improved with FSRS compared to SRS, as evaluated by central review of imaging. IV. To evaluate if there is any difference in central nervous system (CNS) failure patterns (local versus \[vs.\] distant brain failure vs. both) in patients who receive FSRS compared to patients who receive SRS. V. To compare the rates of radiation necrosis in patients who receive FSRS vs. SRS. VI. To compare the time to salvage whole brain radiation therapy (WBRT) between patients who receive FSRS and those who receive SRS. VII. To compare the rates of post-treatment adverse events associated with FSRS and SRS. OUTLINE: Patients are randomized to 1 of 2 arms. ARM I: Patients undergo SRS over 30-90 minutes for 1 fraction on study. Additionally, patients undergo computed tomography (CT) and magnetic resonance imaging (MRI) on study. ARM II: Patients undergo FSRS over 30-90 minutes for 3 fractions on study. Additionally, patients undergo CT and MRI on study. After completion of study treatment, patients are followed up every 3 months for 1 year, every 4 months for 1 year then every 6 months for 3 years.