Evaluation of extraprostatic disease in the staging of prostate cancer by F-18 choline PET/CT: can PSA and PSA density help in patient selection?

Objective The aim of our study was to evaluate the accuracy of F-18 choline positron emission tomography/computed tomography (PET/CT) in assessing the presence of extraprostatic disease during staging of prostate cancer, in relation to prostate-specific antigen (PSA) and PSA density, a PSA derivative that is useful for improving risk stratification in prostate cancer patients. Methods F-18 choline PET/CT was performed in 45 patients for early staging of biopsy-proven prostate cancer. None of the examined patients had received therapy before the examination. In all of them a transrectal ultrasonography had been performed earlier to calculate the prostate volume and PSA density. The mean PSA value was 25.5 (+/- 38.1) ng/ml, whereas the mean PSA density was 0.70 (+/- 0.88). Results Results of F-18 choline PET/CT were related to PSA and PSA density. PET/CT was positive for extraprostatic disease in 18/45 patients (40%) (mean PSA and PSA density were, respectively, 44.08 ng/ml and 1.08); PET/CT was negative for extraprostatic disease in 27/45 patients (60%) (mean PSA and PSA density were, respectively, 13.12 ng/ml and 0.4). PET/CT was positive in 13/18 patients (72%) with a PSA cutoff value greater than or equal to 18 ng/ml and in 5/21 (24%) with a PSA value less than 18 ng/ml (P=0.0017). PET/CT was positive in 16/18 patients (89%) with PSA density greater than or equal to 0.31 and in 2/18 (11%) with PSA density lower than 0.31 (P=0.0234). Conclusion The possibility of detecting extraprostatic disease of prostate cancer with F-18 choline PET/CT is related to PSA and PSA density. In particular, F-18 choline PET/CT should be recommended only in patients with a PSA value of at least 18 ng/ml, whereas a PSA density of at least 0.31 ng/ml is more probably associated with distant metastases.