Comparison of Trelstar Versus Lupron or Zoladex in Advanced Prostate Cancer

Inclusion Criteria: * Advanced Prostate Cancer * Currently taking Lupron or Zoladex * Stable PSA * Baseline testosterone below castration level * Life expectancy \> 6 months * Eastern Cooperative Oncology Group performance status of 0-2 * Signed, approved informed consent. Exclusion Criteria: * Known hypersensitivity to any leuteinizing hormone releasing hormone (LHRH) agonist * Ongoing therapy with hyperprolactinemic agents * Antiandrogen therapy within 28 days prior to study start * Prior Orchiectomy, hypophysectomy or adrenalectomy * Chemotherapy, radiotherapy, or prostatectomy within 28 days prior to study start * Use of any investigational agent 3 months prior to enrollment * Use of systemic corticosteroids within 28 days or during study * Other malignancies within 2 yrs prior to study start, except curatively treated skin cancers * Severe kidney or liver failure, based on adequate lab values * Other medical conditions which would be likely to interfere with compliance or completion of study requirements