Two Doses of Conjugated Estrogen (Premarin) in Patients With Androgen-Independent Prostate Cancer

The purpose of this study is to see if Premarin is useful against androgen-independent prostate cancer and to help understand how drugs such as Premarin may work.

Patients will be randomly assigned to one of two study groups (arm A or Arm B). Arm A will receive 1.25mg of Premarin once daily and arm B will receive 1.25mg of Premarin three times a day. Patients will also receive coumadin daily to help prevent thromboembolic disease. After reviewing the first 30 patients on Arm A, it was determined that arm A (low dose Premarin) was not effective. Arm A was then closed and patients on Arm A were given the choice to switch to Arm B. Treatment will continue until there is evidence of disease progression or unacceptable side effects. Every 4 weeks while receiving Premarin, a physical exam and blood work will be performed. Every 12 weeks a CT scan of the abdomen and pelvis and a bone scan will be performed. Patients will also be encouraged to undergo standard preventative breast irradiation prior to starting Premarin or up to 4 weeks after starting treatment.