PRIAPUS-PCa Study: Stereotactic Body Radiation Therapy (SBRT) and Androgen Deprivation Therapy (ADT) Impact on Sexual Function on Men With Unfavorable Intermediate Risk Prostate Cancer

This study examines how two standard combination treatment for prostate cancer - a highly targeted form of radiation called Stereotactic Body Radiation Therapy (SBRT) and a hormone-blocking treatment called Androgen Deprivation Therapy (ADT) - impact sexual function in men with unfavorable intermediate risk prostate cancer. Participants will complete study questionnaires before treatment or Baseline, and after treatment, on Month 3, 9, 15, and 24.

Inclusion criteria

• Men aged 18-80 years with biopsy-proven UIR-PCa (National Comprehensive Cancer Network [NCCN] criteria: Gleason score 7 (4+3), PSA 10-20 ng/mL, or clinical stage T2b-T2c)
• Planned treatment with SBRT (36.25-37.5 Gy in 5 fractions) and ADT (6 months)
• Baseline sexual function assessment available (International Index of Erectile Function [IIEF-5, also known as SHIM] score ≥ 12 or pre-selection erection status score of 1-3: erection insufficient for intercourse, sufficient but not optimal, or normal)
• Eastern Cooperative Oncology Group (ECOG) performance status 0-1.
• Written informed consent to participate.

Exclusion criteria

• Prior pelvic radiotherapy, prostate surgery, ADT, or chemotherapy
• Pre-existing severe sexual dysfunction (IIEF-5 score < 12 or pre-selection erection status score of 0: no erection)
• Hypogonadism at presentation (baseline testosterone below normal range)
• Contraindications to SBRT or ADT
• Metastatic disease, second malignancy, or previous malignancies.
• Benign or malignant penile diseases.
• Use of medications altering ejaculation (e.g., 5-alpha reductase inhibitors)
• Psychiatric conditions affecting questionnaire completion or QoL assessment
• Severe comorbidities affecting QoL assessments (e.g., advanced cardiovascular disease).