Outcomes of robot-assisted partial nephrectomy for completely endophytic renal tumors: A multicenter analysis

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. 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. 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. 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.

Besides clinical tumour size, other anatomical aspects of the renal tumour are routinely considered when evaluating the feasibility of elective nephron-sparing surgery (NSS). To propose an original, standardised classification of renal tumours suitable for NSS based on their anatomical features and size and to evaluate the ability of this classification to predict the risk of overall complications resulting from the surgery. We enrolled prospectively 164 consecutive patients who underwent NSS for renal tumours at a tertiary academic referral centre from January 2007 to December 2008. Open partial nephrectomy without vessel clamping. All tumours were classified by integrating size with the following anatomical features: anterior or posterior face, longitudinal, and rim tumour location; tumour relationships with renal sinus or urinary collecting system; and percentage of tumour deepening into the kidney. We generated an algorithm evaluating each anatomical parameter and tumour size (the preoperative aspects and dimensions used for an anatomical [PADUA] score) to predict the risk of complications. Overall rates of complication were significantly correlated to all the evaluated anatomical aspects, excluding clinical size and anterior or posterior location of the tumour. By multivariate analysis, PADUA scores were independent predictors of the occurrence of any grade complications (hazard ratio [HR] for score 8-9 vs 6-7: 14.535; HR for score ≥10 vs 6-7: 30.641). Potential limitations were the limited number of patients with T1b tumours included in the study and the lack of laparoscopically treated patients. Further external validation of the PADUA score is needed. The PADUA score is a simple anatomical system that can be used to predict the risk of surgical and medical perioperative complications in patients undergoing open NSS. The use of an appropriate score can help clinicians stratify patients suitable for NSS into subgroups with different complication risks and can help researchers evaluate the real comparability among patients undergoing NSS with different surgical approaches.