PSMA-PET Guided De-escalation of Salvage Radiation Treatment in Recurrent Prostate Cancer

Inclusion Criteria: 1. Prior biopsy proven prostate cancer for which they underwent a radical prostatectomy with curative intent. 2. Evidence of biochemical recurrence as defined by NCCN: Persistent positive PSA post-radical prostatectomy (RP) or an undetectable PSA after RP with a subsequent detectable PSA that increases on ≥2 determinations (PSA recurrence) or increases to PSA \>0.1 ng/mL. 3. Targetable PSMA-avid lesion within the prostate bed, pelvic lymph nodes, or both and/or targetable lesion in prostate bed defined on MRI suspicious for local recurrence. 4. If lesions are amenable for biopsy this may be attempted, but biopsy proven recurrence/persistence is not required for trial enrollment. 5. Life expectancy greater than 5 years. 6. Karnofsky performance status ≥ 80 or Eastern Cooperative Oncology Group performance status ≤ 2 within 14 days prior to registration. 7. Age ≥ 30 years. 8. Patient must be able to provide study-specific informed consent prior to study entry. Exclusion Criteria: 1. Evidence of distant metastatic disease outside the pelvic lymph nodes (including osseous pelvic disease). 2. Presence of any psychological, familial, sociological, or geographical condition potentially hampering compliance with the study protocol and follow-up schedule, including alcohol dependence or drug abuse. 3. Relative or absolute contraindications to radiation therapy as determined by the treating physician. These include but are not limited to inflammatory bowel disease, connective tissue disorders (systemic lupus erythematosus, scleroderma, etc.), and genetic disorders that risk increased sensitivity to radiation therapy.