External Beam Therapy With Theranostic Radioligand Therapy for Oligometastatic Prostate Cancer (ProstACT TARGET)

Inclusion Criteria: * Signed Informed Consent Form * Male, aged ≥ 18 years * Estimated life expectancy of at least 6 months * Eastern Cooperative Oncology Group (ECOG) score 0 - 2 * Biopsy proven prostate adenocarcinoma with Gleason Score 7 or more at primary presentation * Previous Radical Prostatectomy (RP) with curative intent (+/- post-operative radiotherapy to prostate bed) * Biochemical relapse, as defined by EAU-ESTRO-SIOG Guidelines (serum PSA \> 0.2 ng/mL, confirmed by repeat measurements) * PSMA-ligand avid pelvic nodal disease on PSMA-ligand PET/CT, with visualised disease confined to the pelvis with or without evidence of PSMA-avid disease in the prostate bed * At least one pelvic nodal lesion ≥ 5 mm in the greatest dimension. SUVmax \> 9 in enlarged nodes; SUVmax \> 3 in nodes 5 mm or less * Oligometastatic disease as defined by ≤ 5 metastatic lymph nodes * Metastatic lymph nodes not beyond the aortic bifurcation * Non-castrate levels of testosterone (\> 20 ng/dL) * Chemotherapy naïve * Adequate renal function: Cr Cl ≥ 40 mL/min (determined by Cockcroft-Gault formula) * Adequate bone marrow function: Hb \> 90 g/L; platelets \> 100 x 109/L; neutrophils \> 1.5 x 109/L * Adequate liver function: bilirubin \< 1.5 x upper limit of normal (ULN); AST, ALT, ALP \< 2 x ULN; albumin \> 30 g/L * Willing and able to comply with all trial requirements, including all treatments and pre- and post-treatment assessments * Able to commence treatment within 28 days of enrolment E…