A drug used to treat prostate cancer and to relieve the symptoms of advanced breast cancer. It is also used to treat problems with the endometrium (lining of the uterus). Zoladex keeps the body from making the hormones luteinizing hormone-releasing hormone (LHRH) and luteinizing hormone (LH). This causes the testicles to stop making testosterone (a male hormone) in men, and the ovaries to stop making estradiol (a form of the hormone estrogen) in women. Zoladex may stop the growth of cancer cells that need testosterone or estrogen to grow. It is a type of LHRH agonist. Also called goserelin acetate and ZDX.