PD60-11: Impact of the Time Elapsed Between Prostate Biopsy and Surgery on the Accuracy of the Briganti Nomogram Predicting Lymph Node Invasion in men with clinically localized prostate cancer

Giorgio Gandaglia*, Elio Mazzone, Emanuele Zaffuto, Gabriele Sorce, Francesco Pellegrino, Luigi Nocera, Armando Stabile, Umberto Capitanio, Alessandro Larcher, Milan, Italy, Andrea Salonia, Milano, Italy, Federico Dehò, Varese, Italy, Pierre I. Karakiewicz, Montreal, Canada, Shahrokh F. Shariat, Vienna, Austria, Francesco Montorsi, Alberto Briganti, Milano, Italy

Introduction: Nomograms based on preoperative characteristics have been proposed to identify prostate cancer (PCa) patients who should receive a staging extended pelvic lymph node dissection (ePLND) at the time of radical prostatectomy (RP). Although these models are characterized by excellent discrimination for the identification of lymph node invasion (LNI), their accuracy might vary according to the time elapsed between biopsy and surgery. We hypothesized that in men with delayed surgery the accuracy in predicting LNI using a recommended tool decreases due to changes in disease status.

Methods: A total of 3,246 patients with PCa treated with RP between 2000 and 2021 and enrolled in a prospective dataset at a single, tertiary referral center were identified. All patients underwent an anatomically defined ePLND at the time of RP. The risk of LNI was calculated according to the 2012 Briganti nomogram. Patients were stratified according to the time elapsed between biopsy and surgery in 2 groups (=6 months vs. >6 months). Baseline disease characteristics and the risk of upgrading at final pathology was compared between the groups. The characteristics of the Briganti nomogram according to the time between biopsy and surgery was calculated using the ROC-derived area under the curve (AUC) and calibration plots.

Results: Median age and PSA were 66 and 7 ng/ml. Overall, 1,430 (44%), 1,359 (42%) and 457 (14%) had a biopsy ISUP grade group 1, 2-3 and 4-5, respectively. The median LNI risk according to the Briganti nomogram was 10%. Patients treated =6 months after biopsy had a higher proportion of grade group 4-5 disease compared to those treated >6 months (14 vs. 12%; p=0.02). No differences were observed in the LNI risk. The proportion of upgrading at final pathology was similar between the two groups (34 vs. 32%; p=0.2). The discrimination of the Briganti nomogram in predicting LNI was substantially lower in men undergoing surgery >6 months from biopsy compared to those treated within 6 months (87 vs. 81%). Moreover, at calibration plots the nomogram was associated with a substantial underestimation of the risk of LNI in men treated >6 months after biopsy.

Conclusions: Although the Briganti nomogram is characterized by excellent characteristics in predicting the risk of LNI, the discrimination and calibration are suboptimal when considering men undergoing surgery more than 6 months after prostate biopsy. Clinicians should be careful when using this model to select ePLND candidates in the setting of delayed surgery.

Source of Funding: None.