To evaluate the effect of neoadjuvant androgen deprivation treatment (ADT) on prostate-specific membrane antigen (PSMA) tracer uptake demonstrated in Ga-PSMA-positron emission tomography (PET/CT) in non-metastatic hormone-naïve prostate cancer (PC) patients.

The clinical data of 108 PC patients who received neoadjuvant ADT were retrospectively analyzed. All patients had a baseline Ga-PSMA-PET/CT scan, and a second scan was delivered median of 2.9 months after the initiation of ADT. The maximum standardized uptake value (SUV) of primary tumor (SUV) and metastatic lymph nodes (SUV) as well as PSA response were assessed between pre- and post-ADT Ga-PSMA-PET/CT scans.

There were significant decreases in posttreatment serum PSA, SUV, and SUV. A decrease in SUV was seen in 91 patients (84%) with a median value of 66% (range, 5-100%), while 17 patients (16%) had no change in or an increase in PSMA tracer uptake with a median value of 24% (range, 0-198%). Patients with Gleason score (GS) of 7 had significantly higher metabolic response rates compared to other patients. The disease progression was significantly higher only in patients with GS > 7 disease compared to GS 7 disease. The PSA response to ADT was the lowest in patients with ISUP high-grade tumors. A total of 16 patients (15%) had progressive disease, and in 9 patients (8%), radiotherapy decisions were modified according to posttreatment Ga-PSMA-PET/CT scans.

The current study includes the largest number of patients analyzed to date and demonstrates that ADT causes a significant decrease in serum PSA values and SUV and SUV. The authors demonstrate that Ga-PSMA-PET/CT may be used as a quantitative imaging modality after neoadjuvant ADT in hormone-naïve non-metastatic PC patients.