Researchers have developed a standardized scoring system for quantifying renal tumor size, location, and depth.
The new tool, called the R.E.N.A.L.-Nephrometry Score, could improve patient management and enable meaningful comparisons of renal masses in clinical practice and in the urological literature.
“The problem is that our literature is replete with very qualitative terms to describe how difficult a kidney tumor may be [from a surgical perspective],” said Robert G. Uzzo, MD, Chairman of the Department of Surgery at Fox Chase Cancer Center in Philadelphia.
“Many physicians use terms such as ‘endophytic,’ ‘exophytic,’ ‘hilar,’ ‘central,’ or other types of qualitative terms when describing renal tumors. Moreover these descriptive terms are used in concert with highly subjective patient-, family-, or surgeon-specific factors when making decisions regarding partial vs. radical nephrectomy, open vs. minimally invasive approaches, and even which patients are best treated with ablation modalities. This lack of standardization makes it difficult to compare treatment recommendations or the results of published series.”
The new scoring system is based on five critical and reproducible anatomical features of solid renal masses. Four of the components are scored on a three-point scale, with the fifth component indicating the anterior or posterior location of the mass relative to the kidney’s coronal plane.
R.E.N.A.L. is an acronym used to refer to the components of nephrometry. R refers to radius, a measure of tumor size easily obtained on a picture archive and communications system as the maximal diameter of the tumor; E refers to the exophytic/endophytic properties at the deepest location; N refers to the nearness of the tumor’s deepest portion to the collection system or sinus; A refers to a tumor’s anterior/posterior position relative to the axial midline of the kidney; and L refers to a tumor’s location relative to the polar line.
The nephrometry scores range from 4 to 12 points; scores of 4-6, 7-9, and 10-12 translate into low, moderate, and high complexity, respectively, for partial nephrectomy.
A number of published studies have postulated that the pathology of a solid renal mass may be different based upon its size and location within the kidney, said Dr. Uzzo, Medical Director for Urology at Renal & Urology News.
“It may be that tumors with higher nephrometry scores have different pathologies than tumors with lower nephrometry scores,” he added.
If this is the case, nephrometry could aid in establishing a patient’s prognosis. The modality’s primary aim, however, is to standardize the assessment of a lesion’s resectability to help make more meaningful comparisons of treatment recommendations and the literature, Dr. Uzzo pointed out. Efforts are currently under way to validate the scoring system at other institutions.
A detailed explanation of the scoring system by Dr. Uzzo and co-author Alexander Kutikov, MD, also of Fox Chase, is scheduled to be published in the Journal of Urology.
Meanwhile, a description, examples, and an online calculator are available at www.nephrometry.com. Questions or comments on using the R.E.N.A.L. nephrometry score can be submitted on the Web site as well.