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.