Quality of Individual Studies and Determination of Evidence Strength. The systematic review included 303 eligible studies that addressed the pre-identified questions of interest. A large body of evidence evaluated established chemotherapy agents such as docetaxel [19 Randomized controlled trials (RCTs)], estramustine (5 RCTs) and mitoxantrone (5 RCTs). Randomized evidence was also available for various immunotherapies (8 RCTs), therapies targeting the androgen signaling pathway (12 RCTs), radiotherapy and radiopharmaceuticals (4 RCTs) and bone-targeting therapies (6 RCTs). The quality of these trials was acceptable overall and ranged from moderate to low risk of bias. All the remaining studies were otherwise non-randomized (observational) and considered to be at high risk of bias.