REDI-CaP(Recovery of Erectile Dysfunction Induced in Prostate Cancer Patients)

Assessment of the International Index of Erectile Function-5 (IIEF-5) score at six months after hormonal therapy cessation, indicating recovery in at least 70% of the study population. Evaluation of Erectile Function Recovery 6 Months After Hormonal Therapy Completion The success of the study will be determined if erectile function recovery is observed in at least 70% of the population 6 months after the completion of hormonal therapy. Definition of "Erectile Function Recovery" for Individual Patients: A subject will be considered to have recovered erectile function if, at 6 months after the completion of hormonal therapy (Relugolix), their IIEF5 (International Index of Erectile Function - 5) score meets one of the following conditions: * Achieving an IIEF5 score ≥ 17: This score indicates mild erectile dysfunction or no erectile dysfunction (as per IIEF5 categories: 22-25 no erectile dysfunction, 17-21 mild dysfunction). AND/OR; * Significant increase in IIEF5 score compared to baseline: An increase of at least 5 points compared to the baseline (pre-treatment) IIEF5 score, indicating a clinically significant improvement in erectile function. Recovery will only be evaluated in patients who had erectile dysfunction present (IIEF5 \< 22) at baseline. The study will be considered "successful" if the proportion of patients meeting the individual definition of "erectile function recovery" (as specified above) at 6 months after the completion of hormonal therapy is greater than or equal to 70% of the studied population. The secondary endpoints of this study aim to provide a comprehensive understanding of both the functional and oncological outcomes following the cessation of hormonal therapy with Relugolix. One key endpoint is the time to sexual function recovery (SFRT), defined as the interval between hormonal therapy cessation and the point at which a patient achieves an IIEF-5 score of 8 or higher, maintained across two consecutive assessments. This threshold was selected to reflect a clinically meaningful level of erectile function recovery, particularly in patients with moderate to severe dysfunction at baseline, and aligns with established literature and the study's primary endpoint criteria. Recovery will be assessed by comparing post-treatment IIEF-5 scores with each patient's baseline value. Additionally, the study will investigate the correlation between erectile function recovery and radiation dose exposure to critical anatomical structures involved in sexual function, including the penile bulb, crura, internal pudendal arteries, periprostatic neurovascular bundles, and testes, aiming to identify dose-dependent effects on functional outcomes. Other secondary endpoints include biochemical progression-free survival (bPFS), measured according to the Phoenix criteria (nadir PSA + 2 ng/mL), as well as local control (time to local recurrence or last follow-up without recurrence) and distant progression-free survival (dPFS), defined as the time to detection of distant metastases. The study will also evaluate acute and late urinary and rectal toxicity, using the RTOG criteria and International Prostate Symptom Score (IPSS) to assess the genitourinary and gastrointestinal side effects of therapy. To gauge broader patient well-being, quality of life (QoL) will be monitored using validated tools including the EORTC QLQ-C30, EORTC PR25, and IIEF-5 questionnaires. Furthermore, the study incorporates a financial toxicity assessment using the PROFFIT questionnaire, which measures the economic burden of treatment from the patient's perspective. Lastly, overall survival (OS) will be tracked, defined as the time from treatment initiation to death from any cause or the date of last follow-up, thereby offering a complete view of treatment impact across survival, function, toxicity, and patient-reported outcomes.