PSA trend and response to radium-223. The trend in the patient’s PSA over the course of his disease is shown, and the PSA response to radium-223 is highlighted. PSA flared after the first dose of radium-223, peaking at 996 ng/mL 3 weeks after the initiation of therapy. PSA then steadily improved and nadired at 554 ng/mL about 1 month after the 6th dose of radium-223. After completion of radium-223, PSA remained stable at about 600 ng/mL for about 7 months before increasing again.