LAUSR

Introduction PET-CT using 18F-choline is widely used in diagnosis of prostate cancer local recurrence and metastases, whereas Prostate Specific Antigen (PSA) measurement is routinely used for biochemical monitoring. The purpose of our study was to evaluate performance of PET-CT with 18F-choline in relation to the PSA level or its change in time, in patients with biochemically diagnosed recurrent prostate cancer. Material and methods 263 consecutive prostate cancer patients with elevation of PSA after treatment were included into the study. PSA values were evaluated at the time of PET scan (not more than 30 days before) and the PSA level change (ΔPSA) was calculated as a per month difference between two recent measurements. PET-CT was performed using Discovery IQ scanner (GE Healthcare ), 3 and 20 min after injection of 18F-choline (3 MBq/kg). Data are shown as median values (quartiles). Results and discussions In 164 patients, in whom PET-CT scan was positive and has shown local recurrence or metastases both the PSA level [5,85(2,09;17,37)] ng/ml and ΔPSA [0,54 (0,06;2,00)] ng/ml/month were significantly (p<0.01) higher than in 99 subjects with negative PET-CT: 1,23 (0,25;3,59) ng/ml and 0,00 (-0,11;0,10) ng/ml/month, respectively. The ROC curve analysis has indicated that PSA level of 1,70 ng/ml and ΔPSA of 0,12 ng/ml/month are the optimal cut-off values, with sensitivity 80, 9% and 70,2% and specificity 69.1% and 84.3%, for PSA and ΔPSA respectively. Conclusion Diagnostic performance of 18F-choline PET-CT in patients with recurrent prostate cancer is dependent on the level of PSA and its change in time. The calculated cut-off values can be used to select patients who would benefit from PET-CT.