To determine when 18F-choline PET/CT can truly identify local recurrence of prostate cancer.
1031 patients from 3 European centers underwent (18)F-choline PET/CT (FCH PET/CT) for recurrent disease; 131 subjects (12.
7%) showed a positive FCH uptake in the prostatic gland or prostatic fossa. Median age was 72 years (range 48-87 years), and the median PSA level at the time of FCH PET/CT scan was 4. 41 ng/mL (0. 22-18. 13 ng/mL). 45 patients (34. 4%) had a Gleason score (GS) >7, and the residual subjects had a GS ≤7. The assessment of true or false-positive FCH PET/CT findings was made by magnetic resonance imaging (n = 34) and/or biopsy in 75/131 cases. A χ (2) test and a Z Kolmogorov-Smirnov test were used to assess the correlation between clinical variables (age, PSA, GS, type of therapy) and FCH PET/CT findings.
FCH PET/CT resulted truly positive (TP) for recurrent disease in the prostatic gland/fossa in 59/75 patients (79%) and falsely positive (FP) in 16 subjects (21%). The median value of PSA at the time of FCH PET/CT scan was higher in TP as compared to FP, although not statistically significant (4. 76 vs. 3. 04 ng/mL p > 0. 05). Similarly, median age, GS categories, and the type of therapy were similar between the two groups (p > 0. 05). However, when matching GS categories and PSA values, we found that the number of patients with TP findings were higher in the case of a PSA >2 ng/mL, independently from the GS (ranging between 74% and 92%). Conversely, FP rate ranged between 50% and 65% in patients with a PSA ≤2 ng/mL, especially in the case of GS ≤7, whereas FP was around 25% in those with a GS >7 and PSA >2 ng/mL.
FCH PET/CT has a limited role in evaluation of prostatic gland/fossa recurrence, due to the physiological biodistribution of the radiopharmaceutical agent. However, in 70-90% of patients with a PSA >2 ng/mL, independently from GS, a focal FCH uptake is compatible with a true local recurrence.
Abdominal imaging. 2015 Oct 01 [Epub ahead of print]
Laura Evangelista, Marino Cimitan, Marina Hodolič, Tanja Baseric, Jure Fettich, Eugenio Borsatti
Radiotherapy and Nuclear Medicine Unit, Veneto Institute of Oncology IOV - IRCCS, Via Gattamelata, 64, 35128, Padua, Italy. laura. evangelista@ioveneto. it. , Nuclear Medicine Unit, IRCCS National Cancer Institute (CRO), Aviano, PN, Italy. , Nuclear Medicine Research Department, IASON, Graz, Austria. , Nuclear Medicine Unit, IRCCS National Cancer Institute (CRO), Aviano, PN, Italy. , Nuclear Medicine Department, University Medical Center Ljubljana, Ljubljana, Slovenia. , Nuclear Medicine Unit, IRCCS National Cancer Institute (CRO), Aviano, PN, Italy.