68Ga-PSMA-11 PET-CT study in prostate cancer patients with biochemical recurrence and non-contributive 18F-Choline PET-CT: Impact on therapeutic decision-making and biomarker changes.

BackgroundIn this retrospective study, we investigated the impact of Ga-68-PSMA-11 PET-CT (PSMA PET-CT) upon the treatment plan and therapeutic response obtained for Prostate Cancer (PCa) patients presenting an occult biochemical recurrence. MethodsForty-two patients with previously negative or doubtful 18F-Choline (FCH) were enrolled. PET images were recorded 1h after injection of tracer. Only a few months after treatment ended, a PSA assay was requested to evaluate the therapeutic efficacy of the treatment based on PSMA results. ResultsPSMApositive lesions were detected in 34/42 (80.9%) patients. Detection rates were 85.7% and 89.3% for serum PSA levels lower than 2ng/mL, and >2ng/mL, respectively. One hundred seventy-three lesions were detected: 132/173 in lymph nodes (76.3%), 22/173 as metastatic sites (bone or lung) (12.7%), and 19/173 in the prostate bed (10.9%). As a result of the PSMA PET-CT, therapeutic management changed in 31/42 patients (73.8%). With a follow-up of 4.92.27 months, 32/42 (76.2%) PSA assays after treatment guided by PSMA PET-CT were collected. For 37.5% (12/32) of patients, the serum PSA level was lower than 0.2ng/mL and a PSA decrease of over 50% in 8 (25.0%) other patients were obtained. ConclusionPerforming a PSMA PET-CT when FCH PET-CT was doubtful or negative allows the recurrence localization in more 80% of patients and this had a major clinical impact, as it resulted in treatment change in more than 70% of patients as well as a significant decrease in PSA levels in more than 60% of them.