This study is evaluating whether adding stereotactic radiotherapy (a new, more focused type of radiotherapy) to treat all the tumours that are present will improve outcomes or not compared to drugs alone for patients who are negative on conventional imaging and positive on PSMA PET scan

Inclusion Criteria:

1. Age > 18 years.
2. Able to provide informed consent.
3. Histologic diagnosis of prostate adenocarcinoma.
4. ECOG performance status 0-1.
5. Stage IV hormone sensitive, synchronous or metachronous oligometastatic prostate cancer as detected by PSMA PET-CT scan with no metastases visible on conventional imaging (CT chest/abdomen/pelvis and bone scan +/- MRI) performed within 3 months of starting ADT.
6. Up to a maximum of 3 PSMA avid areas of metastatic disease.
7. For patients with metachronous disease, there must be a documented PSA rise. For those who had previous prostatectomy, PSA must be > 0.2 ng/mL. For those who had previous radical radiotherapy, PSA must have risen to at least 2 ng/mL above the nadir (Phoenix definition). The primary tumor must be controlled, with no PSMA avid progression within the primary prostate.
8. All sites of disease are amenable to and can be safely treated with SBRT.

Exclusion Criteria:

1. Significant comorbidities rendering patient not suitable for ADT and/or SBRT.
2. History of malignancy within the past 5 years, excluding non-melanoma skin cancer and in-situ cancer.
3. Prior use of salvage or palliative intent ADT. Prior ADT use allowed only if it was delivered neoadjuvantly, concurrently, or adjuvantly with curative-intent treatment to the prostate or prostate bed (for patients with metachronous presentations), and at least 12 months have elapsed.
4. Castrate resistant prostate cancer.
5. Evidence of spinal cord compression.

Prostate Cancer Patients only. Males only.