New Renal Scoring System Predicts NSS Outcomes
Researchers have developed a new renal scoring system to help physicians determine whether patients are candidates for nephron-sparing surgery (NSS).
The Zonal NePhRO scoring system takes into account four parameters of small renal masses that collectively indicate whether a patient's tumor should be removed. These are the extent of the tumor (‘Ne' – nearness to cortex, medulla and collecting system), whether it includes the collecting system (‘Ph' – physical zones), the tumor's radius (‘R'), and whether the mass is largely exophytic or endophytic (‘O' – organization). Each patient is assigned a score of 1, 2, or 3 for each parameter, with low risk for malignancy being scores of 4-6 points, intermediate risk being scores of 7-9 points and high risk being scores of 10-12.
Lead investigator Philippe E. Spiess, MD, and his collaborators from the Department of Genitourinary Oncology at the Moffitt Cancer Center, Tampa, Fla., created the NePhRO system. They compared it in this study to the older but established and validated R.E.N.A.L. nephrometry scoring system. Spiess and colleagues determined that the NePhRO scoring system is simpler to complete and more accurately predicts the risk of perioperative complications.
“The zonal NePhRO has unique properties which make it advantageous versus other scoring systems for renal cancer surgery such as ease of use, low inter-observer variability, and ability to better discriminate risk of perioperative complications,” said Dr. Spiess, Associate Professor of Genitourinary Oncology, after his team presented the results at the 2013 annual meeting of the Societé Internationale d'Urologie. “We encourage other urologists to assess the presently described zonal NePhRO scoring and determine if this is ultimately a better tool for them in their respective surgical practices.”
The team retrospectively reviewed the scores and outcomes from patients with stage T1a or T1b renal masses who underwent NSS at Moffitt. None of the patients had solitary kidneys or received any other procedures.
The review covered 200 patients who were treated between 2008 and 2011. Their average age was 59.81 years (range 29-85 years), their average tumor size was 3.06 cm (0.8-6.5 cm) , their mean estimated blood loss during the nephrectomy was 293.7 cc (25-2,500 cm) and the mean clamp time was 19.31 minutes (0-57).
Their mean NePhRO score was 8.62 and their mean R.E.N.A.L. nephrometry score was 7.21. The investigators invited other urologists to score each patient; those physicians' mean time to determine the NePhRO score was 15.19 seconds, where it took them an average of 21.15 seconds to determine patients' R.E.N.A.L. scores.
A total of 37 patients were determined to have a low risk on the NePhRO scoring system, while 84 had intermediate-risk masses and 79 had high-risk masses. There was significantly more estimated blood loss with increasing risk level (163.6 cc, 263 cc and 344.3 cc, for low, intermediate and high risk, respectively). None of the low-risk-lesion patients developed a urine leak, whereas four of the intermediate-risk-lesion and six of the high-risk-lesion patients did so. Twenty-five (67.6%) of the low-risk lesions were found to be renal cell carcinoma compared with 57 (67.9%) in the intermediate-risk category and 60 (75.9%) in the high-risk category.
A total of 39 perioperative complications occurred. NePhRO predicted these on both univariate and multivariate analyses. However, the scoring system did not predict urinary leaks, tumor pathological stage, or maximum tumor diameter on multivariate analysis.
“We believe the zonal NePhRO takes into account tumor size in the designation of a given complexity score, and that this is why this endpoint did not come out as predictive in our multivariate model,” Dr. Spiess explained. “We are developing other predictive tools as they pertain to the characteristics of the tumor which may help predict tumor biology and potentially risk of urinary fistulae, and these will likely be integrated in our scoring system in the months to come.”