Inclusion Criteria:

• Metastatic breast cancer (MBC) OR metastatic non-small cell lung cancer (NSCLC) OR metastatic adenocarcinoma of the prostate; the sites of allowed metastases are: peripheral lung, central lung, mediastinal/cervical lymph node, liver, spinal/paraspinal, osseous, and abdominal-pelvic
  • NOTE: after the required number of evaluable patients have been accrued for a given dose level, the accrual for that metastatic location will be temporarily suspended while the safety of that dose level is assessed; a patient can only be entered onto the trial if all of their metastatic locations are open to accrual (e.g. if central lung is temporarily suspended for safety assessment and the patient has a central lung metastases, regardless of other metastases, they cannot enroll until the safety of dose to central lung is determined)
• Primary tumor site without progression at registration
• All metastases not resected must be amenable to SBRT
• The patient must meet ONE of the three following criteria:
  • 3-4 radiographically distinct metastases of any distribution in the allowed anatomical sites OR
  • 2 radiographically distinct metastases that must be anatomically close (i.e., with less than or equal to 5 cm of normal tissue between them) OR
  • 3 or 4 distinct metastasis, 2 or 3 to be treated with SBRT and the other (s) having been surgically removed
• Evaluation by a radiation oncologist within 45 days prior to study registration
• Evaluation by a medical oncologist within 45 days prior to study registration
• The following imaging workup to document metastases within 45 days prior to study registration:
  • Computed tomography (CT) scans of the chest, abdomen and pelvis with radionuclide bone scan OR whole body positron emission tomography (PET)/CT
• History/physical examination within 45 days prior to study registration
• Zubrod performance status ≤ 2 within 45 days prior to study registration
• Age ≥ 18 years
• Absolute neutrophil count (ANC) ≥ 500 cells/mm^3
• Platelets ≥ 50,000 /mm^3
• Hemoglobin ≥ 8.0 g/dl (Note: the use of transfusion or other intervention to achieve hemoglobin [Hgb] ≥ 8.0 g/dl is acceptable)
• If liver metastases present, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) must be < 3 x upper limit of normal (ULN)
• Patient must provide study specific informed consent prior to study entry
• For females of child-bearing potential, negative serum/urine pregnancy test within 14 days prior to study registration

Exclusion Criteria:

• Progression of primary tumor site (breast, prostate, or lung) at time of registration
• Metastases with indistinct borders making targeting not feasible
• Known brain metastases
• Prior palliative radiotherapy to metastases
• Metastases located within 3 cm of the previously irradiated structures:
  • Spinal cord previously irradiated to > 40 Gy
  • Brachial plexus previously irradiated to > 50 Gy
  • Small intestine, large intestine, or stomach previously irradiated to > 45 Gy
  • Brain stem previously irradiated to > 50 Gy
  • Lung previously irradiated with prior volume 20 Gy (V20Gy) > 30%
• Severe, active co-morbidity, defined as follows:
  • Unstable angina and/or congestive heart failure requiring hospitalization within the last 6 months prior to registration
  • Transmural myocardial infarction within the last 6 months prior to registration
  • Acute bacterial or fungal infection requiring intravenous antibiotics at the time of registration
  • Chronic obstructive pulmonary disease exacerbation or other respiratory illness requiring hospitalization or precluding study therapy within 30 days prior to registration
  • Severe hepatic disease, defined as a diagnosis of Child-Pugh class B or C hepatic disease
  • Human immunodeficiency virus (HIV) positive with cluster of differentiation (CD) 4 count < 200 cells/microliter; note that patients who are HIV positive are eligible, provided they are under treatment with highly active antiretroviral therapy (HAART) and have a CD4 count ≥ 200 cells/microliter within 30 days prior to registration; note also that HIV testing is not required for eligibility for this protocol
  • End-stage renal disease (i.e., on dialysis or dialysis has been recommended)
• Pregnancy or women of childbearing potential not willing/able to use medically acceptable forms of contraception during protocol treatment or for at least 6 months following treatment