Inclusion Criteria:

• Male patient must be ≥ 18 years of age.
• 1.  
• Patient must have at least one and up to three asypmtomatic metastatic tumor(s) of the bone or soft tissue (with at least one bone metastasis) develop within the past 6-months that are ≤ 5.0 cm or < 250 cm^3 as seen on either CT/MRI scan and/or bone scan. Up to five lesions are allowed on advanced funcitonal imaging such as fluciclovine (Axumin), choline or 18F-DCFPyL (“PyL”) PET-CT scan. (PET-CT scan is reasonable for study entry imaging as an alternative to CT/MRI scan and/or bone scan).
• Patient must have had their primary tumor treated with surgery and/or radiation.
• Histologic confirmation of malignancy (primary or metastatic tumor).
• PSADT < 15 months. PSA doubling time (PSADT) will be calculated using as many PSA values that are available from time of relapse (PSA > 0.2). To calculate PSADT, the Memorial Sloan Kettering Cancer Center Prostate Cancer Prediction Tool will be used. It can be found at the following web site: https://www.mskcc.org/nomograms/prostate/psa-doubling-time.
• Patient may have had prior systemic therapy and/or ADT associated with treatment of their primary prostate cancer.  Patient may have had ADT associated with salvage radiation therapy (to the primary prostate cancer or pelvis is allowed).
• PSA > 0.5  but < 50.
• Testosterone > 125 ng/dL.
• Patient must have a life expectancy ≥ 12 months.
• Patient must have an ECOG performance status ≤ 2.
• Patient must have normal organ and marrow function as defined as:
  • Before the first administration of Xofigo, the absolute neutrophil count (ANC) should be ≥ 1.5 x 10^9/L;
  • The platelet count ≥ 100 x 10^9; and
  • Hemoglobin ≥ 10 g/dL.
• Patient must have the ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria

• Patient is under 18 years of age.
• No more than 3 years of ADT is allowed, with the most recent ADT treatment having occurred greater than 6 months prior to enrollment.
• PSMA-PET/MRI or PSMA-PET/CT scan within the past 6 months with results that demonstrate more disease lesions than baseline CT/Bone Scan.
• Castration-resistant prostate cancer (CRPC).
• Spinal cord compression or impending spinal cord compression.
• Suspected pulmonary and/or liver metastases (> 10 mm in largest axis).
• Patient receiving any other investigational agents.
• Patient receiving abiraterone and prednisone.
• Patient is participating in a concurrent treatment protocol.
• Serum creatinine > 3 times the upper limit of normal.
• Total bilirubin > 3 times the upper limit of normal.
•  Liver Transaminases > 5-times the upper limit of normal.
•  Unable to lie flat during or tolerate PET/MRI, PET/CT or SBRT.
•  Prior salvage treatment to the primary prostate cancer or pelvis is allowed.
•  Refusal to sign informed consent.