Detection rate of 18F-Choline positron emission tomography/computed tomography in patients with non-metastatic hormone sensitive and castrate resistant prostate cancer.

Aim To assess the detection rate of 18F-choline PET/CT in non-metastatic hormone-sensitive prostate cancer (hsPCa) and non-metastatic castrate resistant prostate cancer (CRPCa), based on the criteria proposed in the phase III SPARTAN trial and with high Gleason Score (GS). Methods Between October 2008 and September 2019, data from a retrospective multicenter study (n=4 centers), involving patients undergoing 18F-choline PET/CT scans for a biochemical recurrence of PCa, were collected. The following inclusion criteria were used: 1) histologically proven PCa, 2) a non-metastatic disease in accordance with conventional imaging findings; 3) a PSA doubling time (PSAdt) 8 and 5) no pelvic node > 2 cm. The group of hsPCa and CRPCa patients, were compared by using a non-parametric statistical analysis. Moreover, a logistic regression analysis and ROC curves were used. Results 140 patients were included. Of these, 82 patients were affected by hsPCa, and 58 had a CRPCa. Overall, 18F-Choline PET/CT was positive in 99/140 (70.7%). It was positive in 55/82 (67.1%) hsPCa patients and in 44/58 (75.9%) CRPCa subjects, respectively. The site of recurrence at 18F-Choline PET/CT were: 16 (27.6%) and 20 (24.4%) in prostatic bed, 25 (43.1%) and 24 (29.3%) in loco-regional lymph nodes and in 27 (46.6%) and 28 (34.1%) in distant organs, respectively for CRPCa and hsPCa patients. The optimal cut-off values for PSA at the time of PET/CT for the prediction or recurrence were 0.5 vs. 2.5 ng/mL for all site of recurrence (AUC: 0.70 vs. 0.72), 0.48 vs. 3.4 ng/mL for prostatic bed (AUC: 0.60 vs. 0.59), 0.5 vs. 1.5 for loco-regional lymph nodes (AUC: 0.62 vs. 0.57) and 2.2 vs. 2.8 ng/mL for distant metastasis (AUC: 0.74 vs. 0.71), respectively in CRPCa and hsPCa (all p=NS). Sensitivities and specificities of 18F-Choline PET/CT for the identification of recurrence disease in all patient population, in hsPCa and CRPCa were 83.7% and 87.5%, 78.9% and 88.9%, 91.4% and 85.7%, respectively. Conclusions the rate of positive 18F-Choline PET/CT is similar in patients with a hsPCa and CRPCa, in case of low PSAdt and high GS. Therefore, non-metastatic PCa patients should be assessed by molecular imaging, in order to adapt the most appropriate therapeutic approach.