The RENAL Nephrometry Score: A Comprehensive Standardized System for Quantitating Renal Tumor Size, Location and Depth

Purpose: Treatment decisions for renal malignancies depend largely on qualitative data, including a description of tumor anatomy and the experience of the treating surgeon. Currently characterization of renal tumor anatomical elements is descriptive and lacks standardization. Surgical decision making and data set comparisons would be significantly enhanced by a consistent, reproducible system that quantitates the pertinent characteristics of localized renal lesions. We have developed and propose a standardized nephrometry scoring system (R.E.N.A.L. Nephrometry Score) to quantify the anatomical characteristics of renal masses on computerized tomography/magnetic resonance imaging. Materials and Methods: The nephrometry score is based on 5 critical and reproducible anatomical features of solid renal masses. Of the 5 components 4 are scored on a 1, 2 or 3-point scale with the 5th indicating the anterior or posterior location of the mass relative to the coronal plane of the kidney. We applied the R.E.N.A.L. Nephrometry Score to 50 consecutive masses resected at Fox Chase Cancer Center. Results: The R.E.N.A.L. Nephrometry Score consists of (R)adius (tumor size as maximal diameter), (E)xophytic/endophytic properties of the tumor, (N)earness of tumor deepest portion to the collecting system or sinus, (A)nterior (a)/posterior (p) descriptor and the (L)ocation relative to the polar line. The suffix h (hilar) is assigned to tumors that abut the main renal artery or vein. The nephrometry scoring system accurately classified the complexity of 50 consecutive tumors undergoing excision at our institution. Conclusions: Standardized reporting of renal tumor size, location and depth is essential for decision making and effective comparisons. The R.E.N.A.L. Nephrometry Score is a reproducible standardized classification system that quantitates the salient anatomy of renal masses. This novel approach for the systematic characterization of renal tumors provides a tool for meaningful comparisons of renal masses in clinical practice and in the urological literature.