Patients were enrolled by ECOG-ACRIN, the Southwest Oncology Group, the Alliance for Clinical Trials in Oncology, and NRG Oncology (a merged group that includes the National Surgical Adjuvant Breast and Bowel Project, the Radiation Therapy Oncology Group, and the Gynecologic Oncology Group) and through the Clinical Trials Support Unit. Eligible patients had a pathological diagnosis of prostate cancer or a clinical scenario consistent with prostate cancer with an elevated prostate-specific antigen (PSA) level; radiologic evidence of metastatic disease; and an ECOG performance-status score of 0, 1, or 2 (on a scale from 0 to 5, with higher scores indicating greater disability; patients with a score of 2 were eligible if the decrement in functioning was due to prostate cancer). Prior adjuvant ADT was allowed if the duration of therapy was 24 months or less and progression had occurred more than 12 months after completion of therapy. Patients who were receiving ADT for meta-static disease were eligible if there was no evidence of progression and treatment had commenced within 120 days before randomization. Organ function that was adequate for docetaxel treatment was required (details are provided in the protocol). All patients provided written informed consent in accordance with institutional and federal guidelines.