[68Ga]Ga-PSMA-11 PET before and after initial long-term androgen deprivation in patients with newly diagnosed prostate cancer: a retrospective single-center study

Abstract

Purpose The study aimed to evaluate the effect of androgen deprivation therapy (ADT) on PSMA imaging and its correlation to the PSA concentration by comparing qualitative and quantitative parameters: SUVmax, SUVmean, PSMA-derived tumor volume (PSMA-TV), total lesion PSMA (TL-PSMA) and molecular imaging (mi)PSMA score. Methods Retrospective analysis of 21 therapy-naïve patients with oligometastatic prostate cancer (median age 70 years) who underwent either [68Ga]Ga-PSMA-11-PET/CT or -PET/MRI before initiation of (T1) as well as during ADT (T2). The median duration of ADT was 155 days (range 61–289 days). All lesions were analyzed using several qualitative and quantitative PET parameters. Results A total of 109 PSMA-positive lesions (24 intraprostatic, 56 lymphonodal and 29 osseous) were visually detected at any of the examinations, while at T2, two new bone lesions were detected in one patient. During ADT, all patients experienced a decrease in their PSA level (median: 29.1 before vs. 0.71 after; p < 0.001). During long-term ADT, a relevant decrease in lesion count occurred, especially in patients with a T2 PSA value < 1 ng/ml (median: 4 vs. 0.9; p = 0.007) and PSMA expression, which resulted in miN- and/or miM-downstaging in 11 patients (52.7%). All analyzed PET parameters correlated strongly with each other. The PSA level at T2 correlated modestly with the decrease in PSMA expression and its derived volumes. Conclusion Post-ADT scans detected, especially in patients with a residual PSA < 1 ng/ml, fewer PSMA-positive lesions with overall lower PSMA expression, regardless of primary tumor site or metastatic sites. None of the PET parameters has proven to be superior, as they all correlated modestly with the PSA value at T2. Thus, the simply acquirable miPSMA score seems to be the most suitable for evaluating the effect of ADT on PSMA expression.

The added value of 18F-FDG PET/CT compared to 68Ga-PSMA PET/CT in patients with castration-resistant prostate cancer

“…However, there were significant differences in PSA and Gleason scores between the two groups. Namely, patients with PSMA-FDG+ lesions had higher PSA than those without (20.8±8.3 vs. 7.5±2.5 ng/mL; P=0.04; Figure 2A); and patients with PSMA-FDG+ lesions had higher Gleason score than those without (9 [8-9] vs. 7 [7][8][9]; P<0.001; Figure 2B).…”

“…At the same time, the effect of ADT on detection efficiency of 68 Ga-prostate specific membrane antigen (PSMA) PET/CT has been controversial. Although some studies show that long-term use of ADT has no effect on 68 Ga-PSMA PET/CT, Afshar-Oromieh et al found that use of long-term ADT could reduce the PSMA uptake and the visibility of tumour lesions in castration-sensitive prostate cancer (8,9). Weber et al observed that 68 Ga-PSMA PET/CT were positive in 75% of early CRPC patients (10).…”

Impact of Three-Month Androgen Deprivation Therapy on [68Ga]Ga-PSMA-11 PET/CT Indices in Men with Advanced Prostate Cancer—Results from a Pilot Prospective Study

“…In our study, two patients (7%) showed complete resolution of PC lesions after ADT. Hoberück et al [ 28 ] conducted a retrospective study in 21 treatment-naïve patients with distant metastases who had undergone PSMA PET imaging before and after ADT (median duration: 155 days). Compared with the baseline, the results revealed a 24.0% and 13.9% decrease in wbPSMA-TV and wbPSMA-TL values, respectively.…”

18F-DCFPyL PET/CT in Newly Diagnosed Prostate Cancer: Diagnostic Value of Intraprostatic PSMA Uptake in Risk Classification of Prostate Cancer

“…Consequently, we introduced the volumetric parameters like PSMA-TV (16) and TL-PSMA, referring to the product of PSMA-TV and the SUVmean of the lesion. The concepts of these molecular volumes are derived from FDG imaging, and the calculation of PSMA-TV equals to molecular tumor volume (MTV) (11). At the same time, the calculation of TL-PSMA is equivalent to the total lesion glycolysis (TLG).…”

“…As far as we know, there are few related studies. So, we compared the maximal standardized uptake value (SUVmax), mean SUV (SUVmean), total lesion (TL)-PSMA, PSMA-derived tumor volume (PSMA-TV), and prostate/ muscle (P/M) ratio of primary PCa patients with different risks to find the more potential parameter (10)(11)(12).…”