Predictive factors of [18F]-Choline PET/CT in 170 patients with increasing PSA after primary radical treatment

The purpose of this study was to evaluate the potential usefulness of [18F]-Choline PET/CT in the restaging of prostate cancer patients, who presented a rising PSA. We evaluated 170 prostate cancer patients, previously radically treated, that were referred for restaging with [18F]-Choline PET/CT. A total of 129 patients (median PSA 4.29 ng/ml at relapse) showed one or more areas of high uptake on PET/CT scan, while 41 patients with a median PSA of 1.07 ng/ml at relapse showed negative PET/CT scans. No false negative was found, while 31 patients were identified as false positive. Specificity of Choline PET/CT in our series was 56.9 %, while sensibility was 100 %. At the time of restaging, a PSA value superior or equal to 1 ng/ml was found to be a statistically significant predictive factor of PET positivity, either at the univariate (p < 0.0001) and at the multivariate analysis (p < 0.0001). Based on our findings, [18F]-Choline PET/CT is confirmed as a useful diagnostic tool to detect early recurrence, in patients with increasing PSA after primary treatment. However, in case of a mild increase in PSA, positive results must be validated with other techniques, as specificity and positive predictive value of [18F]-Choline PET/CT decrease with the lower values of PSA.