Tumour size outperforms nephrometry scores to predict surgical success following partial nephrectomy

To evaluate the utility of tumour size, R.E.N.A.L. (Radius, Exophytic/Endophytic, Nearness to collecting system or sinus, Anterior/Posterior, Location), PADUA (Preoperative Aspects and Dimensions Used for an Anatomical), and SPARE (Simplified PADUA R.E.N.A.L.) nephrometry scoring systems (NSs) in predicting the likelihood of achieving trifecta and pentafecta outcomes, as well as the risk of postoperative acute kidney injury (AKI) and kidney disease progression at 12 months following robot-assisted partial nephrectomy (RAPN).

Retrospective review was performed on Institutional Review Board-approved, prospectively maintained database to identify all cases of primary, non-metastatic renal masses who underwent RAPN between 2011 and 2024. All preoperative radiological images were reviewed by a single resident physician, who characterised all tumours based on the NSs. Trifecta outcome was defined as cases with warm ischaemia time of <25 min, negative surgical margin, and absence of complications. Pentafecta included the trifecta outcomes with the addition of >90% renal function preservation and absence of kidney disease progression at 12 months. Logistic regression and receiver operating characteristic (ROC) analyses were completed to determine the predictive ability for the tumour size and each of the NSs.

Based on 1787 patients, trifecta and pentafecta were achieved in 52.7% and 22.2%, respectively. All three NSs were established as significant predictors of trifecta, pentafecta, and postoperative AKI, with all demonstrating comparable yet limited predictive performance (area under the ROC curve [AUC] 0.573-0.645). Tumour diameter (AUC 0.649-0.665) was shown to outperform the NSs in predicting the likelihood of achieving trifecta and pentafecta, as well as the risk of AKI. None of the NSs were identified as predictors of kidney disease progression at 12 months.

Although lower R.E.N.A.L., PADUA, and SPARE NSs were associated with achieving surgical success and reduced risk of AKI, their predictive performance was modest and can be outperformed by a simpler and more objective measure, such as tumour diameter. Future studies remain necessary to re-evaluate the broader clinical utility of NSs in predicting surgical and functional outcomes, in addition to its original purpose as standardized tools for the anatomical characterization of renal tumours.