This research study is evaluating a drug called enzalutamide in combination with external
beam radiation therapy as a possible treatment for prostate cancer. Presently, when
participants receive hormonal therapy with radiation therapy for prostate cancer, medications
are given to reduce testosterone levels in the blood stream. This leads to side effects such
as loss of sex drive, erectile dysfunction (ED) and decrease in muscle strength. The purpose
of this study is test another form of hormonal therapy with radiation therapy. The medication
called enzalutamide will be used with radiation therapy. Instead of lowering testosterone,
enzalutamide blocks testosterone in cells. This study will test if enzalutamide when used
with radiation will lower the PSA without causing the side effects associated with
medications that lower testosterone in the blood stream.