Early detection of prostate cancer recurrence following radical prostatectomy: the role of 18F-choline PET/CT

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Introduction: The diagnostic potential of positron emission tomography (PET)/computed tomography (CT) in patients with increasing prostate-specific antigen (PSA) serum levels after radical prostatectomy (RP) is currently under debate. However, evidences supporting the use of this imaging technique in patients with PSA levels <1ng/mL are lacking. We prospectively investigated the role of 18F-Fluorocholine PET/CT in the early (PSA< 1 ng/ml) detection of tumor recurrence after RP. Material & Methods: Between March 2007 and December 2010, 146 consecutive patients with PSA levels between 0.2 and 1 ng/mL, who did not receive adjuvant treatments after RP and with negative conventional imaging were enrolled. Univariable and multivariable analyses were performed to identify independent predictors of positive PET/CT. Sensitivity, specificity, positive and negative predictive values of PET/CT, PSA serum levels before and after 18F-Fluorocholine PET/TC, PSA doubling time (PSA-DT) and PSA velocity (PSA-V) after PET-CT. Results: Median trigger PSA was 0.6 ng/ml (IQR: 0.43 – 0.76). Median PSA-DT was 7.91 months (IQR: 4.42- 11.3), median PSA-V was 0.02ng/ml/month (IQR: 0.02 – 0.04). Overall, 18F-Fluorocholine PET/CT was positive in 111/146 (76%) patients, 99 of which (89.2%) on prostatic fossa, 5 (4.5%) on regional nodes, 1 on bone and 6 (5.4%) on multiple sites. (Tab.1)Sensitivity, specificity, positive and negative predictive values (NPV) and accuracy were 79.4%, 70.0%, 97.3%, 20.0% and 78.7%, respectively. At multivariable logistic regression, trigger PSA ≥0.6 (OR 3.13, 95% CI 1.55–6.31, p=0.001) and PSA-V ≥0.04 (OR 4.95, 95% CI 1.65–14.83, p=0.004) were found to be significant predictors of positive PET/CT. The low NPV remains the main limitation of PET-CT in this setting of patients. Conclusions: The high accuracy in patients with PSA level <1 ng/ml supports 18F-Fluorocholine PET/CT as a valid option in the early detection of PCa recurrence after RP. ==fine abstract==