Comprehensive Versus Primary Tumor Radiotherapy in Oligometastatic Prostate Cancer

Inclusion Criteria: * Male patients aged 18-85 years. * Histopathologically confirmed acinar adenocarcinoma of the prostate. The presence of a minor component of ductal adenocarcinoma, intraductal carcinoma, and/or neuroendocrine differentiation is permitted. * PSMA PET performed within 4 weeks prior to the start of study drug therapy or up to 4 weeks after initiation, demonstrating the presence of 1 to 10 metastatic lesions.Metastasis within pelvic lymph nodes (N1 disease) is permitted but not counted towards the total number of metastatic lesions. Metastasis to non-regional lymph nodes is permitted and counted towards the total number.The pelvis is anatomically divided into 4 regions: left hemipelvis (ilium/ischium/pubis), right hemipelvis (ilium/ischium/pubis), sacrum, and coccyx. Multiple lesions within a single anatomical division are aggregated and counted as one metastatic lesion. * Prior androgen deprivation therapy (ADT) is permitted if the total duration was ≤ 12 months before enrollment. ADT includes luteinizing hormone-releasing hormone (LHRH) agonists or antagonists and novel hormonal agents (e.g., abiraterone, enzalutamide, apalutamide, darolutamide). * Eastern Cooperative Oncology Group (ECOG) score 0-2. * Hematology: Neutrophil count \>=1.0×10\^9/L; Platelet count \>=75×10\^9/L; Hemoglobin \>=90 g/L. Exclusion Criteria: * Small cell carcinoma of the prostate or prostate sarcoma. * The primary focus has received external radiation therapy, brachytherapy, and radical prostatectomy. * Received non-endocrine systemic therapies prior to enrollment (e.g., chemotherapy, targeted therapy, radionuclide therapy). * Metastatic castration-resistant prostate cancer (mCRPC) phase (EAU Guidelines\*). * Presence of visceral metastases (e.g., liver, lung). * Previous bilateral orchiectomy. * Comorbidities: Severe comorbidities affecting survival or treatment tolerance, including: Cardiovascular diseases (NYHA Class III/IV heart failure, uncontrolled arrhythmias); Renal insufficiency (eGFR \<30 mL/min/1.73m\^2); Neuropsychiatric disorders impairing protocol compliance. * Definition of mCRPC (EAU Guidelines): Metastatic castration-resistant prostate cancer (mCRPC) is defined as disease progression despite serum testosterone levels below 50 ng/dL (or 1.7 nmol/L), concurrently with one or more of the following: 1. PSA progression: A sequence of at least three consecutive rises in PSA, measured ≥1 week apart, resulting in a ≥50% increase from the nadir (lowest) level, with a minimum absolute PSA value \>2 ng/mL. 2. Radiographic progression: The appearance of new lesions, defined as either: * ≥2 new lesions on bone scan (Tc-99m bone scintigraphy), or * New measurable soft tissue lesions according to RECIST (Response Evaluation Criteria in Solid Tumors) 1.1 criteria. 3. Unequivocal clinical progression: Clinical progression in the absence of concurrent PSA or radiographic progression should be viewed with suspicion and mandates further investigation to confirm disease progression.