The feasibility of [18F]PSMA-1007 PET/CT for response assessment in prostate cancer following neoadjuvant androgen deprivation therapy compared with mpMRI.

BACKGROUND

We investigated the utility of 18F-labeled prostate-specific membrane antigen positron emission tomography/computed tomography ([18F]PSMA-1007 PET/CT) for assessing residual tumor burden after neoadjuvant androgen deprivation therapy (nADT), compared with multiparametric magnetic resonance imaging (mpMRI).

METHODS

This retrospective study included 20 patients with prostate cancer treated with nADT followed by radical prostatectomy. All patients underwent baseline mpMRI, post-nADT mpMRI, and [18F]PSMA-1007 PET/CT. Lesion-based diagnostic performance of [18F]PSMA-1007 PET/CT and mpMRI was compared using generalized estimating equations. Apparent diffusion coefficient (ADC) and transfer constant (Ktrans) values were compared between baseline and post-nADT using Wilcoxon signed-rank tests and between tumor and benign prostatic hyperplasia (BPH) using Mann-Whitney U tests.

RESULTS

Baseline mpMRI identified 23 biopsy-confirmed lesions, and post-nADT, 21 showed residual tumor on pathology. [18F]PSMA-1007 PET/CT demonstrated significantly higher sensitivity (90.5% vs. 23.8%, p < 0.001) and accuracy (87.0% vs. 26.1%, p < 0.001) than mpMRI. Median ADC increased significantly after nADT (0.849 to 1.174 × 10- 3 mm2/s, p = 0.005), while median Ktrans decreased (0.277 to 0.080 min- 1, p = 0.005). Baseline ADC and Ktrans differed significantly between tumor and BPH (p = 0.001 and p = 0.012, respectively), but no significant post-nADT differences were observed (p = 0.831 and p = 0.701, respectively). Post-nADT SUVmax also did not differ between tumor and BPH (p = 0.639).

CONCLUSIONS

[18F]PSMA-1007 PET showed higher sensitivity and accuracy than mpMRI in detecting residual tumor after short-term nADT and may be useful for further management planning. These preliminary findings support the feasibility of [18F]PSMA-1007 PET for post-treatment assessment.