RAdium-223 and SABR Versus SABR for Oligometastatic Prostate Cancers

Inclusion Criteria:

* Patient must have at least one and up to three asymptomatic 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 cm3
* 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 be ≥ 18 years of age.
* 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 109/L, the platelet count ≥ 100 x 109/L and hemoglobin ≥ 10 g/dL.

\* Patient must have the ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

* 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 (greater \>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.