Role for (11)C-choline PET in active surveillance of prostate cancer.

Introduction: Active surveillance (AS) is an increasingly popular management strategy for men diagnosed with low-risk indolent prostate cancer. Current tests (prostate-specific antigen [PSA], clinical staging, and prostate biopsies) to monitor indolent disease lack accuracy. C-11-choline positron emission tomography (PET) has excellent detection rates in local and distant recurrence of prostate cancer. We examine C-11-choline PET for identifying aggressive prostate cancer warranting treatment in the AS setting. Methods: In total, 24 patients on AS had clinical assessment and PSA testing every 6 months and C-11-choline PET and prostate biopsies annually. The sensitivity and specificity to identify prostate cancer and progressive disease (PD) were calculated for each C-11-choline PET scan. Results: In total, 62 biopsy-paired, serial C-11-choline PET scans were analyzed using a series of standard uptake value-maximum (SUVmax) cut-off thresholds. During follow-up (mean 25.3 months), 11 of the 24 low-risk prostate cancer patients developed PD and received definitive treatment. The prostate cancer detection rate with C-11-choline PET had moderate sensitivity (72.1%), but low specificity (45.0%). PD prediction from baseline C-11-choline PET had satisfactory sensitivity (81.8%), but low specificity (38.5%). The addition of clinical parameters to the baseline C-11-choline PET improved specificity (69.2%), with a slight reduction in sensitivity (72.7%) for PD prediction. Conclusions: Addition of C-11-choline PET imaging during AS may help to identify aggressive disease earlier than traditional methods. However, C-11-choline PET alone has low specificity due to overlap of SUV values with benign pathologies. Triaging low-risk prostate cancer patients into AS versus therapy will require further optimization of PET protocols or consideration of alternative strategies (i.e., magnetic resonance imaging, biomarkers).