Detection of recurrence sites using ¹⁸F-fluorocholine PET/CT in prostate cancer patients with PSA failure

The optimal condition for the clinical application of ¹⁸F-fluorocholine positron emission tomography-computed tomography (FCH-PET/CT) to detect recurrence sites in prostate-specific antigen (PSA) failure remains unclear due to the heterogeneity of prostate cancer failure. We aimed to evaluate the detection rate of FCH-PET/CT in prostate cancer patients with PSA failure and to determine the optimal PSA level for performing FCH-PET/CT.

FCH-PET/CT was conducted in 89 patients diagnosed with PSA failure after radical treatment (radical prostatectomy in 75 and definitive radiotherapy in 14) between November 2018 and May 2021. Detection rates were examined via receiver operating characteristic (ROC) analysis, and multivariable logistic regression was performed to identify factors affecting positive FCH-PET/CT findings. We also conducted subgroup analyses according to the PSA failure patterns after the radical treatment (persistently high PSA [N = 48] and biochemical recurrence [BCR] [N = 41]).

FCH-PET/CT demonstrated a 59.6% overall detection rate, and the optimal PSA threshold for detecting positive findings was ≥ 1.00 ng/mL at the time of imaging. On multivariable analysis, PSA > 1.00 ng/mL (P < 0.001) was a significant predictor of positive FCH-PET/CT findings, especially regarding distant bone metastases (P < 0.001) and recurrence outside the pelvis (P < 0.001). In a subgroup analysis of patients with BCR after initial radical treatment, the area under the ROC curve (AUC) was 0.82, and PSA ≥ 1.75 ng/mL was the optimal value for identifying positive FCH-PET/CT findings. This PSA value was also associated with significantly higher detection rates of distant bone metastases and outside-pelvis metastasis (P < 0.001, both).

FCH-PET/CT is a clinically useful tool for detecting tumor recurrence sites in prostate cancer patients with PSA failure if PSA has exceeded a certain value at the time of imaging. Particularly, higher AUC values were observed when FCH-PET/CT was performed in patients with BCR after initial treatment.