Provenge (sipuleucel-t) vaccine. Ed is a very common problem related to treatments for prostate cancer -that include surgery , radiation ( external /brachytherapy), hormonal therapy and chemotherapy. Prostate cancer is dependent to testosterone. Treatment is aimed to lower it to the castration level. Low testosterone will cause impotency, ed. For selected patient with metastatic disease-immunotherapy with Provenge (sipuleucel-t) can be given.