A drug used to treat prostate cancer that has spread to other parts of the body and did not respond to hormone therapy and certain anticancer drugs. It is also being studied in the treatment of breast cancer and other types of cancer. Zytiga blocks tissues from making androgens (male hormones), such as testosterone. This may stop the growth of cancer cells that need androgens to grow. Zytiga is a type of antiandrogen. Also called abiraterone acetate.