Inclusion Criteria

• Age ≥ 18 years old
• Diagnosis of Brain Metastases
  • Presence of presumed brain metastases from an extra-cerebral tumor site (e.g. lung, breast, prostate, etc.).
  • Note: Dural based metastases (e.g. commonly seen in breast cancer) are eligible.
• Size of Brain Metastases
  • At least one intact metastasis (not previously treated with radiosurgery) must measure > 2.0 cm and < 4.0 cm in maximal extent on the contrasted pre-treatment MRI brain scan obtained ≤ 28 days prior to registration.
  • If the largest lesion measures ≥ 2.0 to < 4.0 cm in maximal extent the patient will be randomized.
• Able to undergo contrast enhanced MRI Brain
• Negative urine or serum pregnancy test completed ≤7 days prior to registration, for women of childbearing potential only
• Patient willing and able to provide written informed consent
• Karnofsky Performance Status (KPS) ≥ 50
• ECOG Performance Score of (PS) ≥ 2
• Past radiosurgery or resection is allowed as long as no definitive evidence of progression in these locations.
  • Note: Repeat radiosurgery to the same location/lesion is not allowed on this protocol.

Exclusion Criteria

• Any patient who has received previous whole brain radiation
• Any brain metastasis that is located in the brainstem measuring ≥ 2.0 cm in maximal extent.
• Any patient with definitive evidence of leptomeningeal metastasis (LMD).

NOTE: For the purposes of exclusion, LMD is a clinical diagnosis, defined as positive CSF cytology and/or unequivocal radiologic or clinical evidence of leptomeningeal involvement. Patients with leptomeningeal symptoms in the setting of leptomeningeal enhancement by imaging (MRI) would be considered to have LMD even in the absence of positive CSF cytology, unless a parenchymal lesion can adequately explain the neurologic symptoms and/or signs. In contrast, an asymptomatic or minimally symptomatic patient with mild or nonspecific leptomeningeal enhancement (MRI) would not be considered to have LMD. In that patient, CSF sampling is not required to formally exclude LMD, but can be performed at the investigator’s discretion based on level of clinical suspicion.{Kim, 2017 #2840}

• Any patient with an intact brain metastasis measuring > 4.0 cm