Early lesion detection with ${}^{18}$F-DCFPyL PET/CT in 248 patients with biochemically recurrent prostate cancer

Prostate-specific membrane antigen (PSMA) PET/CT is increasingly used in patients with biochemically recurrent prostate cancer (BCR), mostly using gallium-68 (${}^{68}$Ga)-labelled radiotracers. Alternatively, fluorine-18 (${}^{18}$F)-labelled PSMA tracers are available, such as ${}^{18}$F-DCFPyL, which offer enhanced image quality and therefore potentially increased detection of small metastases. In this study we evaluate the lesion detection efficacy of ${}^{18}$F-DCFPyL PET/CT in patients with BCR and determine the detection efficacy as a function of their PSA value. A total of 248 consecutive patients were evaluated and underwent scanning with ${}^{18}$F-DCFPyL PET/CT for BCR between November 2016 and 2018 in two hospitals in the Netherlands. Patients were examined after radical prostatectomy (52%), external-beam radiation therapy (42%) or brachytherapy (6%). Imaging was performed 120 min after injection of a median dose of 311 MBq ${}^{18}$F-DCFPyL. In 214 out of 248 PET/CT scans (86.3%), at least one lesion suggestive of cancer recurrence was detected ('positive scan'). Scan positivity increased with higher PSA values: 17/29 scans (59%) with PSA values <0.5 ng/ml; 20/29 (69%) with PSA 0.5 to <1.0 ng/ml; 35/41 (85%) with PSA 1.0 to <2.0 ng/ml; 69/73 (95%) with PSA 2.0 to <5.0 ng/ml; and 73/76 (96%) with PSA ≥5.0 ng/ml. Interestingly, suspicious lesions outside the prostatic fossa were detected in 39–50% of patients with PSA <1.0 ng/ml after radical prostatectomy (i.e. candidates for salvage radiotherapy). ${}^{18}$F-DCFPyL PET/CT offers early detection of lesions in patients with BCR, even at PSA levels <0.5 ng/ml. These results appear to be comparable to those reported for ${}^{68}$Ga-PSMA and ${}^{18}$F-PSMA-1007, with potentially increased detection efficacy compared to ${}^{68}$Ga-PSMA for patients with PSA <2.0.