Abstract
Purpose
To perform an external validation of a recently published nomogram aimed to predict positive 68Ga-PSMA-11 PET/CT in patients with biochemical recurrence (BCR) after radical prostatectomy (RP) by Rauscher et al. (Eur Urol 73(5):656–661, 2018).
Methods
Overall, 413 PCa patients with BCR after RP (two consecutive PSA ≥ 0.2 ng/ml) and PSA value between 0.2 and 1 ng/ml were included. A multivariable logistic regression model was produced to assess the predictors of positive 68Ga-PSMA-11 PET/CT results. The performance characteristics of the model were assessed by quantifying the predictive accuracy, according to model calibration. Yuden’s index was used to find the best nomogram’s cut-off. Finally, decision curve analysis (DCA) was implemented to quantify the nomogram’s clinical value.
Results
In the external cohort, the overall detection rate of 68Ga-PSMA-11 PET/CT was 44% vs. 64.7% in the original population. At multivariate analysis, PSA at 68Ga-PSMA-11 PET/CT (OR: 7.06, p < 0.001) and ongoing ADT at time of 68Ga-PSMA-11 PET/CT (OR: 2.07, p = 0.03) were the only independent predictors of PET/CT positivity. The predictive accuracy of nomogram was suboptimal and comparable to that reported in the original model (64% vs. 67%, respectively). The calibration plot indicated suboptimal concordance. The best nomogram’s cut-off to predict positive 68Ga-PSMA-11 PET/CT was 35% (AUC = 0.61). In DCA, the nomogram revealed clinical net benefit when the threshold probabilities of positive 68Ga-PSMA-11 PET/CT is > 35%.
Conclusion
We assessed similar suboptimal predictive accuracies in the external cohort compared to the original one. PSA and ongoing ADT were confirmed as positive predictors, and the most informative nomogram cut-off resulted 35%.
References
Ost P, Bossi A, Decaestecker K, et al. Metastasis-directed therapy of regional and distant recurrences after curative treatment of prostate cancer: a systematic review of the literature. Eur Urol. 2015;67(5):852–63.
Ost P, Reynders D, Decaestecker K, et al. Surveillance or metastasis-directed therapy for oligometastatic prostate Cancer recurrence: a prospective, randomized, multicenter phase II trial. J Clin Oncol. 2018;36(5):446–53.
Ceci F, Castellucci P, Graziani T, et al. (68)Ga-PSMA-11 PET/CT in recurrent prostate cancer: efficacy in different clinical stages of PSA failure after radical therapy. Eur J Nucl Med Mol Imaging. 2019;46(1):31–9.
Calais J, Ceci F, Eiber M. (18)F-fluciclovine PET-CT and (68)Ga-PSMA-11 PET-CT in patients with early biochemical recurrence after prostatectomy: a prospective, single-Centre, single-arm, comparative imaging trial. Lancet Oncol. 2019;20(9):1286–94.
Farolfi A, Ceci F, Castellucci P, et al. (68)Ga-PSMA-11 PET/CT in prostate cancer patients with biochemical recurrence after radical prostatectomy and PSA <0.5 ng/ml. Efficacy and impact on treatment strategy. Eur J Nucl Med Mol Imaging. 2019;46(1):11–9.
Suardi N, Gandaglia G, Gallina A, et al. Long-term outcomes of salvage lymph node dissection for clinically recurrent prostate cancer: results of a single-institution series with a minimum follow-up of 5 years. Eur Urol. 2015;67(2):299–309.
Ceci F, Bianchi L, Borghesi M, et al. Prediction nomogram for (68)Ga-PSMA-11 PET/CT in different clinical settings of PSA failure after radical treatment for prostate cancer. Eur J Nucl Med Mol Imaging. 2019. https://doi.org/10.1007/s00259-019-04505-2.
Rauscher I, Duwel C, Haller B, et al. Efficacy, predictive factors, and prediction nomograms for (68)Ga-labeled prostate-specific membrane antigen-ligand positron-emission tomography/computed tomography in early biochemical recurrent prostate cancer after radical prostatectomy. Eur Urol. 2018;73(5):656–61.
Fendler WP, Calais J, Eiber M, et al. Assessment of 68Ga-PSMA-11 PET accuracy in localizing recurrent prostate cancer: a prospective single-arm clinical trial. JAMA Oncol. 2019;5(6):856–63.
Emmett LM, Yin C, Crumbaker M, Hruby G, Kneebone A, Epstein R, et al. Rapid modulation of PSMA expression by androgen deprivation: serial (68)Ga-PSMA-11 PET in men with hormone sensitive and castrate resistant prostate cancer commencing androgen blockade. J Nucl Med. 2018.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of interest
The authors declare that they have no conflict of interest.
Ethical approval
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the principles of the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
Informed consent
Informed consent was obtained from all individual participants included in the study.
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
This article is part of the Topical Collection on Oncology – Genitourinary
Rights and permissions
About this article
Cite this article
Bianchi, L., Borghesi, M., Schiavina, R. et al. Predictive accuracy and clinical benefit of a nomogram aimed to predict 68Ga-PSMA PET/CT positivity in patients with prostate cancer recurrence and PSA < 1 ng/ml external validation on a single institution database. Eur J Nucl Med Mol Imaging 47, 2100–2105 (2020). https://doi.org/10.1007/s00259-020-04696-z
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00259-020-04696-z