A drug used with prednisone to treat prostate cancer that has spread to other parts of the body and has not gotten better with other hormone therapy. 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.