Impact of 18F-choline PET/CT in prostate cancer patients with biochemical recurrence: influence of androgen deprivation therapy and correlation with PSA kinetics

Abstract

We evaluated the potential of (18)F-fluoromethyldimethyl-2-hydroxyethyl-ammonium (FCH) PET/CT in the detection of recurrent disease or distant metastases and correlated its diagnostic accuracy with prostate-specific antigen (PSA) levels in prostate cancer patients with biochemical evidence of recurrence. Furthermore, the influences of androgen deprivation therapy (ADT) and its duration on (18)F-FCH PET were assessed in this study.

Methods: This prospective study included 250 prostate cancer patients with PSA relapse who underwent (18)F-FCH PET/CT. At the time of (18)F-FCH PET/CT imaging, the mean PSA level was 46.9 ± 314.7 ng/mL and 55.2% (138/250) of patients were receiving ADT. Overall, ADT was performed on 67.2% (168/250) of patients after initial treatment. Imaging was performed on an integrated PET/CT system. Acquisition started 1 min after intravenous injection of (18)F-FCH (4.07 MBq/kg of body weight) with dynamic PET images in the pelvic region during 8 min (1 min/frame) followed by a static semi-whole-body acquisition. The final diagnosis of positive PET lesions was based on histopathology or a consensus of clinical findings, additional imaging, or follow-up imaging modalities.

Results: (18)F-FCH PET/CT was able to correctly detect malignant lesions in 74% (185/250) of patients but was negative in 26% (65/250). In 28% of patients, only 1 lesion was detected (69/250); from these, 65.2% (45 patients) had a local recurrence, 18.8% (13 patients) a single lymph node, and 15.9% (11 patients) a solitary bone metastasis. The sensitivity of the (18)F-FCH PET was significantly higher (P = 0.001) in patients with ongoing ADT (85%; confidence interval, 80%-91%) than in patients without ADT (59.5%; confidence interval, 50%-69%). (18)F-FCH PET sensitivity was 77.5%, 80.7%, 85.2%, and 92.8% for the trigger PSA levels of more than 0.5, 1.0, 2.0, and 4.0 ng/mL, respectively. Scan sensitivity was 33% in patients with a trigger PSA level of less than 0.3 ng/mL and 77% in patients with a trigger PSA level of greater than 0.3 ng/mL, respectively (P = 0.001). Using a binary logistic regression analysis model, we showed trigger PSA and ADT to be the only significant predictors of positive PET findings.

Conclusion: (18)F-FCH PET/CT proved its potential as a noninvasive 1-stop diagnostic modality enabling us to correctly detect occult disease in 74% of patients and to differentiate localized from systemic disease. In patients with biochemical recurrence, it also guides to an optimal treatment approach after initial treatment. Trigger PSA and ADT are the 2 significant predictors of (18)F-FCH-positive PET lesions. ADT seems not to impair (18)F-FCH uptake in hormone-refractory prostate cancer patients.

Keywords: 18F-choline PET/CT; PSA kinetics; androgen deprivation therapy; prostate cancer recurrence.