Purpose

This randomized phase III trial studies how well stereotactic body radiation therapy works compared to intensity-modulated radiation therapy in treating patients with stage IIA-B prostate cancer. Radiation therapy uses high energy x-rays to kill tumor cells and shrink tumors. Stereotactic body radiation therapy is a specialized radiation therapy that sends x-rays directly to the tumor using smaller doses over several days and may cause less damage to normal tissue. Stereotactic body radiation therapy may work better in treating patients with prostate cancer.