Author(s): Castellucci P, Fuccio C, Nanni C, Santi I, Rizzello A,
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Abstract The purpose of this study was to investigate the effect of total prostate-specific antigen (PSA) at the time of (11)C-choline PET/CT (trigger PSA), PSA velocity (PSAvel), and PSA doubling time (PSAdt) on (11)C-choline PET/CT detection rate in patients treated with radical prostatectomy for prostate cancer, who showed biochemical failure during follow-up. METHODS: A total of 190 patients treated with radical prostatectomy for prostate cancer who showed an increase in PSA (mean, 4.2; median, 2.1; range, 0.2-25.4 ng/mL) were retrospectively enrolled. All patients were studied with (11)C-choline PET/CT. Patients were grouped according to trigger PSA (PSA = 1 ng/mL, 1 < PSA = 2 ng/mL, 2 < PSA = 5 ng/mL, and PSA > 5 ng/mL). In 106 patients, data were available for calculation of PSAvel and PSAdt. Logistic regression analysis was used to determine whether there was a relationship between PSA levels and PSA kinetics and the rate of detection of relapse using PET. RESULTS: (11)C-choline PET/CT detected disease relapse in 74 of 190 patients (38.9\%). The detection rate of (11)C-choline PET/CT was 19\%, 25\%, 41\%, and 67\% in the 4 subgroups-PSA = 1 ng/mL (51 patients), 1 < PSA = 2 ng/mL (39 patients), 2 < PSA = 5 ng/mL (51 patients), and PSA > 5 ng/mL (49 patients)-respectively. Trigger PSA values were statistically different between PET-positive patients (median PSA, 4.0 ng/mL) and PET-negative patients (median PSA, 1.4 ng/mL) (P = 0.0001). Receiver-operating-characteristic analysis showed an optimal cutoff point for trigger PSA of 2.43 ng/mL (area under the curve, 0.76). In 106 patients, PSAdt and PSAvel values were statistically different between patients with PET-positive and -negative scan findings (P = 0.04 and P = 0.03). The (11)C-choline PET/CT detection rate was 12\%, 34\%, 42\%, and 70\%, respectively, in patients with PSAvel < 1 ng/mL/y (33 patients), 1 < PSAvel = 2 ng/mL/y (26 patients), 2 < PSAvel = 5 ng/mL/y (19 patients), and PSAvel > 5 ng/mL/y (28 patients). The (11)C-choline PET/CT detection rate was 20\%, 40\%, 48\%, and 60\%, respectively, in patients with PSAdt > 6 mo (45 patients), 4 < PSAdt = 6 mo (20 patients), 2 < PSAdt = 4 mo (31 patients), and PSAdt = 2 mo (10 patients). There was no statistical difference between PET-positive and -negative scan detection rates according to the Gleason score, pT and N status, patient age, or duration between surgery and biochemical relapse. Trigger PSA and PSAvel were found to be independent predictive factors for a PET-positive result (P = 0.002; P = 0.04) and PSAdt was found to be an independent factor only in patients with trigger PSA less than 2 ng/mL (P = 0.05) using multivariate analysis. CONCLUSION: The (11)C-choline PET/CT detection rate is influenced by trigger PSA, PSAdt, and PSAvel. This finding could be used to improve the selection of patients for scanning by reducing the number of false-negative scans and increasing the detection rate of disease in patients with early relapse and potentially curative disease.
This article was published in J Nucl Med
and referenced in Journal of Nuclear Medicine & Radiation Therapy