- Patients must have had a history of a response to medical or surgical castration therapy for prostate cancer with a serum PSA nadir of </= 0.2 ng/ml and must not have had any known subsequent rise in serum PSA level of any magnitude above this nadir within the first 24 months of hormonal therapy. Nadir PSA value following hormonal therapy in combination with non-hormonal therapy such as radical prostatectomy, radiation therapy or chemotherapy do not count towards eligibility.