AUA 2022: Development of a Novel Nomogram to Identify Candidates for Extended Pelvic Lymph-Node Dissection in Prostate Cancer using MRI and PSMA PET

( In a moderated poster presentation at the 2022 American Urologic Association Annual Meeting held in New Orleans and virtually, Dr. Dennie Meijer described the development of a novel nomogram to identify patients for extended pelvic lymph-node dissection (ePLND) at the time of radical prostatectomy using magnetic resonance imaging (MRI) and prostate-specific membrane antigen (PSMA)-positron emission tomography (PET).

The authors used a cohort of men who underwent MRI and PSMA-PET prior to radical prostatectomy (RARP) and ePLND to develop a novel prognostic model for predicting pathological lymph-node (pN)-status. Beyond these imaging characteristics, the authors further included preoperative clinical and histopathological parameters in their nomogram. Logistic regression with backward elimination was used to select variables for the prognostic model. The performance of the final resulting model was evaluated using the area under the receiver operating characteristic curve (AUC) and decision-curve analyses (DCAs).

The authors used a cohort of 700 consecutive patients who underwent robot-assisted radical prostatectomy (RARP) and ePLND to derive this nomogram. Among these 700 men, 185 patients (26%) were found to have pN1-disease at the time of surgery.

Following backward elimination variable selection, the final model included initial prostate-specific antigen (PSA)-value, radiological T-stage on MRI, highest biopsy Grade Group (GG), biopsy technique (MRI-targeted versus systematic), percentage of systematic cores with clinically significant PCa (≥GG2) and PSMA-PET findings as predictors of lymph node involvement. The resulting model had an AUC for predicting pN-status of 0.82 (95% CI 0.78-0.85).


Further, the DCA demonstrated an increased net-benefit of ePLND with the threshold probability ≥3%. Using a cut-off of 7% above which to perform ePLND, 16% of ePLNDs could have been correctly avoided. Using 10% as a cut-off to prompt ePLND, 34% of ePLNDs would be spared, in exchange for 5.5% of patients with pelvic lymph-node metastatic disease.

Dr. Meijer concluded therefore that this novel nomogram outperforms currently available models to predict lymph node involvement of prostate cancer and, when used, would be able to avoid ePLND in a substantial proportion of patients.

Presented by: Dennie Meijer, Cancer Center Amsterdam

Written by: Christopher J.D. Wallis, University of Toronto Twitter: @WallisCJD during the 2022 American Urological Association (AUA) Annual Meeting, New Orleans, LA, Fri, May 13 – Mon, May 16, 2022

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