High-dose Brachytherapy Boost With Stereostatic Body Radiation Therapy to Intermediate or Higher Risk Prostate Cancer

This study is testing a combination of high-dose brachytherapy (internal radiation placed directly in the prostate) with stereotactic body radiation therapy (SBRT, a highly precise external radiation technique) for intermediate- to high-risk prostate cancer, to see if this approach controls cancer while minimizing side effects. **You may be eligible if...** - You have been diagnosed with prostate cancer classified as unfavorable intermediate, high, or very high risk (based on standard medical criteria) - This is your first treatment for prostate cancer — you have not had prior surgery, radiation, or hormone therapy - Your life expectancy is estimated to be more than 10 years - Imaging shows no cancer spread to lymph nodes or distant organs **You may NOT be eligible if...** - You have already had treatment for prostate cancer - Your cancer has spread beyond the prostate - You have health conditions that make radiation treatment unsafe Talk to your doctor to see if this trial is right for you.