Relationship between prostate-specific antigen kinetics and detection rate of radiolabelled choline PET/CT in restaging prostate cancer patients: a meta-analysis

Background: The aim of the article was to systematically review published data about the relationship between prostate-specific antigen (PSA) kinetics, including PSA doubling time (PSAdt) and PSA velocity (PSAvel), and detection rate (DR) of positron emission tomography/computed tomography (PET/CT) using radiolabelled choline in restaging prostate cancer (PCa). Methods: A comprehensive literature search of studies published through July 2013 regarding the relationship between PSA kinetics and DR of radiolabelled choline PET/CT was carried out. Furthermore, a meta-analysis was performed in order to establish the DR of radiolabelled choline PET/CT using different cut-off values of PSAdt (<= or >6 months) and PSAvel [>1 or <= 1 ng/(mL year) and >2 or <= 2 ng/(mL year)]. Moreover, a pooled analysis to establish whether PSAdt and PSAvel (using the abovementioned cut-off values) may predict positive PET/CT results was carried out. Results: Fourteen articles were selected. The pooled DR of radiolabelled choline PET/CT in restaging PCa was 58% [95% confidence interval (CI) 55-60]. Most articles reported a relationship between PSA kinetics and DR of PET/CT. Pooled DR of radiolabelled choline PET/CT increased to 65% (95% CI 58-71) when PSAdt was <= 6 months and to 71% (95% CI 66-76) and 77% (95% CI 71-82) when PSAvel was >1 or >2 ng/(mL year), respectively. PSAdt <= 6 months and PSAvel >1 or >2 ng/(mL year) proved to be relevant factors in predicting the positive result of radiolabelled choline PET/CT. Conclusions: Due to the strong relationship between PSA kinetics and DR of radiolabelled choline PET/CT, beyond PSA values, PSAdt and PSAvel should be taken into account in the selection of PCa patients who should undergo radiolabelled choline PET/CT for restaging.