title: Influence of trigger PSA and PSA kinetics on 11C-Choline PET/CT detection rate in patients with biochemical relapse after radical prostatectomy.
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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Nuclear Medicine Unit, Hematology-Oncology and Laboratory Medicine Department, Azienda Ospedaliero-Universitaria di Bologna Policlinico S. Orsola-Malpighi, University of Bologna, Bologna, Italy. paolo.castellucci@aosp.bo.it
authors.forename: Paolo
authors.initials: P
authors.lastname: Castellucci
authors.forename: Chiara
authors.initials: C
authors.lastname: Fuccio
authors.forename: Cristina
authors.initials: C
authors.lastname: Nanni
authors.forename: Ivan
authors.initials: I
authors.lastname: Santi
authors.forename: Anna
authors.initials: A
authors.lastname: Rizzello
authors.forename: Filippo
authors.initials: F
authors.lastname: Lodi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Franceschelli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Martorana
authors.forename: Fabio
authors.initials: F
authors.lastname: Manferrari
authors.forename: Stefano
authors.initials: S
authors.lastname: Fanti
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D002794:Choline / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000097:blood* / Q000175:diagnosis* / Q000517:prevention & control; D049268:Positron-Emission Tomography / Q000379:methods*; D017430:Prostate-Specific Antigen / Q000097:blood*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis* / Q000601:surgery; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D017430:Prostate-Specific Antigen; D002794:Choline