The current study is a randomized phase II study comparing high speed, single arc, LINAC-based prostate stereotactic ablative radiotherapy (SABR) with conventional external beam radiation treatment (EBRT), along with androgen suppression (AS), in men with intermediate and high risk prostate cancer, who are either unsuitable for or unwilling to have brachytherapy. The two primary objectives of the study are to assess the feasibility of randomization, and to compare the rates of acute and late toxicities. Should randomization prove feasible, and toxicities comparable, a future phase 3 trial will be pursued.