Radium-223-Dichloride in Castration Resistant Metastatic Prostate Cancer-Preliminary Results of the Response Evaluation Using F-18-Fluoride PET/CT

The purpose of this study was to evaluate the outcome after Radium-223-dichloride ((223)RaCl₂) treatment of patients with skeletal metastases of castration resistant prostate cancer using whole-body (18)F-Fluoride PET/CT. Sodium (18)F-fluoride [(18)F]-NaF PET/CT was performed prior the treatment of (223)RaCl₂, after the first cycle and after the sixth cycle. The skeletal metastases were analyzed quantitatively using modified PET response evaluation PERCIST criteria. The patients were also analyzed for S-PSA. All ten patients responded in [(18)F]-NaF scans after 6 cycles, but interim analysis after the 1st cycle did not give additional information about the outcome. The S-PSA decrease correlated with [(18)F]-NaF response, only 1 patient demonstrated progressive disease, i.e., >25% increase in S-PSA values during (223)RaCl₂. Our results (although preliminary) suggest that (18)F-Fluoride PET/CT is useful in the follow-up of castration resistant prostate cancer with skeletal metastases.