Prostate-Specific Antigen Velocity Versus Prostate-Specific Antigen Doubling Time for Prediction of 11C Choline PET/CT in Prostate Cancer Patients With Biochemical Failure After Radical Prostatectomy

Abstract

We previously showed that prostate-specific antigen (PSA) doubling time (PSADT) is a significant predictor of 11C choline positron emission tomography/computed tomography (PET/CT) findings in prostate cancer (PCa) patients. This study compared PSA velocity (PSAV) and PSADT to predict 11C choline PET/CT findings. PSAV and PSADT were retrospectively calculated in 170 PCa patients with biochemical failure after radical prostatectomy, who underwent 11C choline PET/CT for restaging of disease. Median PSA was 1.25 ng/mL (range: 0.23-48.6 ng/mL), and median PSAV was 0.99 ng/mL/y (range: 0.11-98.9 ng/mL/y). Patients with positive 11C choline PET/CT (n = 75) had significantly (P < 0.05) higher PSAV than patients with negative 11C choline PET/CT (n = 95) (6.93 ± 13.08 vs. 1.23 ± 2.03 ng/mL/y). The percent of patients with positive 11C choline PET/CT was 21% for PSAV <1 ng/mL/y, 56% for PSAV between 1 and 2 ng/mL/y, and 76% for PSAV >2 ng/mL/y. The quality of fitting (r2) of PSA values according to the exponential function (PSADT) was significantly (P < 0.05) better than the quality of fitting according to the linear function (PSAV) in the entire sample and in all anatomic regions. At multivariate analysis, trigger PSA, PSADT but not PSAV obtained the statistical significance (P < 0.05). PSAV can be used to stratify the risk of positive 11C choline PET/CT in PCa patients with biochemical failure. Patients with PSAV >1 ng/mL/y should be selected to increase the positive detection rate of 11C choline PET/CT. The greater statistical power of PSADT compared with PSAV could be related to the better capability of fitting time-dependent changes in PSA values, thereby better reflecting the natural growth of recurrent PCa.