Serum androgen levels have been shown to be prognostic for overall survival in 1,195 patients with metastatic castration-resistant prostate cancer in a phase III study of abiraterone acetate plus prednisone versus prednisone alone. A baseline serum androgen level above median (median levels of testosterone, androstenedione, and dehydroepiandrosterone sulfate were 5.0 ng/dL, 23.7 ng/dL, and 16 μg/dL, respectively) was associated with longer survival in both treatments arms.