A drug used with prednisone to treat prostate cancer that has spread to other parts of the body. It is used in patients whose cancer is castration resistant (has not responded to treatments that lower testosterone levels) or whose cancer is high risk and castration sensitive (has responded to treatments that lower testosterone levels). It is also being studied in the treatment of other types of cancer. Abiraterone acetate lowers the amount of androgens (male hormones), such as testosterone, made by the body. This may stop the growth of cancer cells that need androgens to grow. Abiraterone acetate is a type of antiandrogen. Also called Zytiga.