The Best Timing of 18F-Choline PET/CT for Patients with Prostate Cancer after Radical Prostatectomy, Radiotherapy and Cryotherapy during Biochemical Relapse

Objectives: :This study was aimed to investigate what factors will influence the detection rate and when is the best timing to perform 18F-choline (18F-CH) PET/CT in patients with biochemical recurrence (BCR) of prostate cancer (PCa) following radical prostatectomy (RP) as well as radiotherapy (RT) and cryotherapy. Methods:From Jan, 2012 to Aug, 2017, 137 scans matching the inclusion criteria, which was proven BCR (PSA>0.2 ng/mL after RP or Phoenix criterion after RT and cryotherapy), were analysed. Three groups of patients classified by initial treatments with RP, RT or cryotherapy were evaluated. Clinical / pathological parameters including PSA nadir, PSA at CholPET, relative PSA (by subtracting the nadir from PSA at CholPET), time from PSA nadir to PSA at CholPET, Gleason score and ongoing androgen deprivation therapy (ADT) were analyzed using univariate and multivariate binary logistic regression to estimate independent predictive factors for positive 18F-CH findings. Receiver Operator Characteristics (ROC) curves were generated by the performance of 18F-CH PET/CT in relation to the PSA levels at the time of the scans. The best PSA cut-off values were determined using Youden’s index. Results:All demographic data were summarized in Table 1. In RP, RT and cryotherapy groups, 59.2%, 92.9% and 82.6% of the 18F-CH PET/CT scans were positive, respectively. In 65.5%, 35.9% and 13.2% of the scans, at least one extra-pelvic finding was noticed. The univariate and multivariate analysis for each variable to predict positive 18F-CH PET/CT were outlined in Table 2. Only the time from PSA nadir to PSA at CholPET in RP group was statistically significant (95% CI, 1.03-1.55), P