Radiotherapy After Prostatectomy for Node Positive Prostate Cancer

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.