Focal Radiotherapy for Previously Treated Prostate Cancer Patients

This trial uses targeted radiation therapy (stereotactic body radiotherapy, or SBRT) to treat a small area of prostate cancer that has come back after previous radiation treatment, aiming to destroy the recurring tumor while sparing surrounding healthy tissue and avoiding the side effects of whole-prostate or systemic treatment. **You may be eligible if...** - You are a man whose prostate cancer has come back after external beam radiation therapy (at least 4–5 years after treatment) - The recurrence is confined to less than half of one side of the prostate, confirmed by both a PSMA PET scan and MRI - Your recurring tumor has been confirmed by biopsy - Your PSA (prostate-specific antigen, a blood marker for prostate cancer) is below 10 - Your life expectancy is at least 10 years **You may NOT be eligible if...** - The recurrence is very close to the rectum (unless a protective gel spacer can be placed) - You experienced severe side effects (grade 3 or higher) from your previous radiation treatment - You cannot safely have fiducial markers (small tracking seeds) placed in the prostate - You previously had the most aggressive type of prostate cancer (Gleason score 8, 9, or 10) Talk to your doctor to see if this trial is right for you.