Radiotherapy After Prostatectomy for Node Positive Prostate Cancer

The goal of this clinical trial is to evaluate whether the addition of pelvic radiotherapy to androgen deprivation therapy (ADT) can delay disease progression and improve survival outcomes in patients with pathologically confirmed regional lymph node-positive (pN1) prostate cancer after radical prostatectomy. The main questions it aims to answer are: * Does ADT combined with pelvic radiotherapy improve biochemical recurrence-free survival (bRFS) compared with ADT alone in pN1 patients? * Does the addition of pelvic radiotherapy improve clinical progression-free survival, metastasis-free survival, overall survival, and prostate cancer-specific survival without unacceptable toxicity? Researchers will compare ADT plus pelvic radiotherapy with ADT alone to see if combined treatment improves disease control and long-term clinical outcomes. Participants with positive lymph nodes after prostatectomy will be randomly assigned in a 2:1 ratio to receive ADT plus pelvic radiotherapy, or ADT alone. ADT will be administered for 2 years. Patients with radiologically detectable pelvic recurrence or distant metastases after radical prostatectomy will be excluded. Safety, adverse events, and health-related quality of life will be assessed during follow-up.

Inclusion Criteria: * Age ≥ 18 years. * Histologically confirmed adenocarcinoma of the prostate. * Radical prostatectomy with pelvic lymph node dissection and pathologically confirmed positive pelvic lymph nodes (AJCC 8th edition: external iliac, internal iliac, obturator, presacral, periprostatic, and/or perirectal nodes). * ECOG performance status 0-2. * Started postoperative GnRH agonist or antagonist therapy for less than 1 year if receiving postoperative androgen deprivation therapy\*. * Adequate major organ function, defined as: Hemoglobin ≥ 90 g/L Platelet count ≥ 75 × 10⁹/L Total bilirubin ≤ 3 × ULN AST or ALT ≤ 5 × ULN * Use of effective contraception during the study and for 3 months after. * Written informed consent provided, with willingness and ability to comply with study visits, treatments, and procedures. * Prior postoperative ARAT use ≤ 3 months is eligible after treatment discontinuation. Exclusion Criteria: * Measurable pelvic recurrence on postoperative MRI or CT (RECIST 1.1, including prostate bed and lymph nodes). * Radiographically confirmed distant metastasis (M1a, M1b, or M1c). * Neoadjuvant hormonal therapy \> 3 months before prostatectomy. * Malignancy within 5 years that may interfere with study safety or efficacy assessments. * Castration-resistant prostate cancer (CRPC) prior to enrollment per 2025 EAU criteria * Prior radiotherapy overlapping irradiation fields that may compromise normal tissue. * Serious comorbidities affecting study treatment. * Psychiatric disorders preventing understanding or compliance. * Any condition that, in the investigator's judgment, makes participation unsuitable.