GOSERELIN (Zoladex® 3.6 mg Implant, Zoladex® 3-month Implant) is a man-made protein that is like a hormone in the body called gonadotropin-releasing hormone (GnRH). Regular injections of goserelin decrease the levels of testosterone in men and estrogen in women. Goserelin can be used for the relief of endometriosis, or for the treatment of prostate cancer and breast cancer. Women receive the Zoladex® 3.6 mg implant only, and injections are given every 4 weeks. Men may receive the Zoladex® 3.6 mg implant every 4 weeks, or may receive a Zoladex® 3-month implant instead. Generic goserelin implants are not yet available.