What approach would you take for patients with metastatic castration-resistant prostate cancer with marked PSA response (undetectable) on docetaxel, but radiographic progression in bone metastases?  

As a first step I would confirm that the patient has truly had radiographic progression of his bone metastases. Prostate cancer can often demonstrate what has been termed a "healing flare" following response to systemic therapy, and radiographic progression in bone requires a follow up bone scan (us...