Image-guided, Tumor-focused Radiotherapy Treatment in Intermediate and High-risk Prostate Cancer

This is a phase II non-blinded randomized controlled trial of image-guided, tumor-focused radiotherapy in patients with intermediate- or high-risk prostate cancer planning to undergo definitive radiotherapy with or without systemic therapy. The image-guided, tumor-focused radiotherapy will be compared to standard, whole-prostate treatment. The investigators hypothesize that tumor-focused radiotherapy reduces the radiation dose to organs close to the prostate, possibly leading to decreased acute toxicity to the genitourinary and gastrointestinal organs. The investigators will measure acute and late genitourinary and gastrointestinal toxicity due to radiation and regardless of cause. The investigators will also measure overall survival, metastasis-free survival, and quality of life, as well as biomarkers that may help predict, in the future, who may have a worse toxicity following radiation therapy.