Evaluation of factors predicting pelvic lymph node involvement in prostate cancer and comparison of nomograms for lymph node dissection decision

Aim: This study aimed to predict pathologic lymph node involvement (pN1) in patients undergoing radical prostatectomy and extended pelvic lymph node dissection (ePLND) for prostate cancer (PCa) and to compare nomograms used in ePLND decision-making. Material and Method: Data from 191 PCa patients undergoing radical prostatectomy and ePLND between 2018 and 2023 were retrospectively analyzed. Clinical, histopathological, PSMA/PET-CT, and MpMR findings were assessed for pN1 prediction and nomogram comparison. Statistical analyses included the Mann-Whitney U test, chi-square test, and multivariate logistic regression. New models incorporating PSMA/PET-CT parameters into the Amsterdam-Brisbane-Sydney nomogram were evaluated using the area under curve (AUC) in 139 patients in secondary analysis. Results: pN1 was present in 35 patients (18.3%), with significant predictors including positive core percentage, Grade group≥2 cores on biopsy, clinical stage, PSMA/PET-CT detected lymph node involvement, clinical stage by MpMR, and maximum index lesion diameter (p<0.05). AUC values for Briganti-2012, Briganti-2017, MSKCC, and Amsterdam-Brisbane-Sydney nomograms were 0.751, 0.722, 0.725, and 0.862, respectively. In secondary analysis, the PRIMARY score was significantly higher in the pN1 group (p=0.011). The AUC of the new model incorporating PRIMARY score into the Amsterdam-Brisbane-Sydney nomogram was 0.870, surpassing other models. Conclusion: The Amsterdam-Brisbane-Sydney nomogram outperformed the Briganti-2012, Briganti-2017, and MSKCC nomograms in predicting pN1. The addition of the PRIMARY score improved the performance of the Amsterdam-Brisbane-Sydney nomogram. These findings suggest that the PRIMARY score and the Amsterdam-Brisbane-Sydney nomogram show promise in pN1 prediction. To our knowledge, this is the first study to investigate the relationship between PRIMARY score and pN1.