Efficacy, Predictive Factors, and Prediction Nomograms for ⁶⁸Ga-labeled Prostate-specific Membrane Antigen–ligand Positron-emission Tomography/Computed Tomography in Early Biochemical Recurrent Prostate Cancer After Radical Prostatectomy

Recently, ⁶⁸Ga-labeled prostate-specific membrane antigen (PSMA)–ligand positron-emission tomography (PET) imaging has been shown to improve detection rates in recurrent prostate cancer (PC). However, published studies include only small patient numbers at low prostate-specific antigen (PSA) values. For this study, 272 consecutive patients with biochemical recurrence after radical prostatectomy and PSA value between 0.2 and 1 ng/ml were included. The ⁶⁸Ga-PSMA-ligand PET/computed tomography (CT) was evaluated, and detection rates were determined and correlated to various clinical variables using univariate and multivariable analyses. Subgroups of patients with very low (0.2–0.5 ng/ml) and low (>0.5–1.0 ng/ml) PSA values were analyzed. In total, lesions indicative of PC recurrence were detected in 55% (74/134) and 74% (102/138) with very low and low PSA values, respectively. Main sites of recurrence were pelvic or retroperitoneal lymph nodes metastases, followed by local recurrence and bone metastases with higher probability in the low versus very low PSA subgroup. Detection rates significantly increased with higher PSA values, primary pT ≥ 3a, primary pN+ disease, grade group ≥4, previous radiation therapy, and concurrent androgen deprivation therapy (ADT) in univariate analysis. In a multivariable logistic regression model, concurrent ADT and PSA values were identified as most relevant predictors of positive ⁶⁸Ga-PSMA-ligand PET/CT. Further, prediction nomograms were established, which may help in estimating pretest PSMA-ligand PET positivity in clinical practice. Patient summary: In our study, ⁶⁸Ga-labeled prostate-specific membrane antigen (PSMA)–ligand positron-emission tomography (PET)/computed tomography (CT) detected recurrent disease after radical prostatectomy in 55% (74/134) and 74% (102/138) of patients with very low (0.2–0.5 ng/ml) and low (>0.5–1.0 ng/ml) prostate-specific antigen values, respectively. On the basis of these data, it seems reasonable to perform ⁶⁸Ga-PSMA-ligand PET/CT also in patients with early biochemical recurrence, as it can tailor further therapy decisions (eg, local vs systemic treatment). The established prediction nomograms can further assist urologists in discussions on the use of ⁶⁸Ga-PSMA-ligand PET/CT with their patients in specific clinical settings. The ⁶⁸Ga-labeled prostate-specific membrane antigen (PSMA)–ligand positron-emission tomography (PET)/computed tomography identifies recurrent prostate cancer after radical prostatectomy even at low prostate-specific antigen (PSA) values in a relevant number of patients. Concurrent androgen deprivation therapy and PSA value were identified as most relevant predictors for PSMA-ligand PET positivity.