F-NaF/RaCl theranostics in metastatic prostate cancer: treatment response assessment and prediction of outcome.

Theranostics refers to companion agents with identical or similar structure targeted to a specific biological entity for imaging and treatment. Although the concept has a long history with radioiodine in thyroidology, but it has experienced remarkable recent renaissance in management of neuroendocrine tumors and prostate cancer. Bone scintigraphy based on osteoblastic reaction and targeted radionuclide therapy with the alpha-particle calcium-mimetic agent, RaCl, also form a theranostic model for imaging and treatment of osseous metastatic disease. Since the regulatory approval of RaCl in 2013, there has been accumulating evidence on the potential use of F-NaF PET scintigraphy in the assessment of response and prediction of outcome in males with metastatic castrate-resistant prostate cancer who undergo RaCl therapy. We review the F-NaF/RaCl as theranostic companion in the management of prostate cancer with emphasis on the utility of F-NaF and other relevant PET radiotracers in the therapy response and prognosis assessments.