Purpose: To evaluate fluorine-18 fluorocholine (FCH) PET/CT for the detection of recurrent prostate cancer in relation to prostate-specific antigen (PSA) level.
Methods: FCH PET/CT was performed in 50 patients with rising PSA levels at follow-up of primary treatment of prostate cancer (radical prostatectomy in 28, radiation therapy in 13, and brachytherapy in 9). PET detection rates were determined at various PSA thresholds and examined by receiver operating characteristic analysis.
Results: Findings consistent with recurrent prostate cancer were noted on FCH PET/CT in 31/50 (62%) patients, with positive findings in 17/18 (94%), and 11/13 (85%), 2/7 (29%), and 1/12 (8%) patients with PSA >4, >2-4, >0.5-2, and ≤0.5 ng/mL, respectively. These findings were indicative of local/regional recurrence in 23 cases and systemic recurrence in 8 cases, with only a single route of recurrence (i.e., either hematogenous, lymphatic, or intraprostatic) in 84% of PET scans with positive findings. Abnormal tumor activity was detected in 88% of patients with a PSA level of 1.1 ng/mL or higher, and in only 6% of patients with a PSA level below this threshold value.
Conclusion: FCH PET/CT may serve to identify the route of tumor progression in patients with recurrent prostate cancer; however, the likelihood of tumor detection may be related to the PSA level at the time of imaging.