Comparing R.E.N.A.L., PADUA, and RPN Scores: Is RPN the More Logical Choice in the Robotic Era?

Abstract

Background and objective: Since their introduction in 2009, first-generation nephrometry systems, the Radius, Exophytic/endophytic, Nearness to collecting system or sinus, Anterior/posterior, Location (R.E.N.A.L.) and Preoperative Aspects and Dimensions Used for an Anatomical Classification (PADUA), have dominated the academic landscape in providing a structured manner to characterise kidney cancers. Their use has extended to predicting perioperative outcomes of partial nephrectomies (PN). In 2022, the Radius, Position of the tumour, iNvasion of renal sinus (RPN), a new nephrometry system was introduced to streamline the process of evaluating renal tumours for their surgical difficulty specific to the robot-assisted laparoscopic approach, with clinically relevant validation. This paper critically compares these three nephrometry systems in terms of their aims, methodologies, performance in validation studies and ease of use.

Methods: Key information about the nephrometry systems was extracted into a table. Categories compared include nomenclature, tumour-specific characteristics, use of suffixes, methodological differences, validation, and ease of use.

Key findings and limitations: The comparison of the R.E.N.A.L., PADUA, and RPN nephrometry systems highlights distinct differences in their methodologies and objectives. While the R.E.N.A.L. and PADUA systems focus on aiding decision-making and data reporting for PN, neither system is specific to the robot-assisted approach. In contrast, the RPN system is specifically tailored for robot-assisted partial nephrectomy (RAPN), aiming to assess preoperative surgical difficulty and ensure consistency in reporting data for RAPN series. Further validation is needed to elucidate the RPN system's utility in modern RAPN practice.

Conclusion: In the current era of RAPN, surgeons require a simple and easy to use nephrometry system to evaluate a renal tumour's surgical complexity quickly and accurately. RPN demonstrates promise in fulfilling this role.