Renal nephrometry score and predictors of pathologic upstaging in patients undergoing partial and radical nephrectomies.

Abstract

412 Background: To examine the predictive capability of pre-operative anatomic imagining characterization of the R.E.N.A.L. Nephrometry Score (RNS) in assessing pathologic upstaging of clinical T1 (cT1) lesions to pathologic T3 (pT3) in partial and radical nephrectomy specimens. Methods: We conducted a retrospective review of all patients undergoing radical and partial nephrectomies between January 1, 2011 and May 31, 2014 for cT1 renal masses. All pre-operative imaging scans were reviewed and the R.E.N.AL. Nephrometry score (radius for tumor size as maximal diameter, exophytic/endophytic tumor properties, nearness of deepest portion of tumor to collecting system or sinus, anterior/posterior descriptor and location relative to polar line) was applied to each scan. Chi-square, Fisher exact test, and Student t test were utilized to examine associations. Results: Of the 229 patients who underwent partial or radical nephrectomy for cT1, 124 (54%) underwent partial nephrectomy. On pathologic evaluation 195 (85%) patients had malignancy. Of all tumors 26 (13%) were pathologically upstaged to pT3 with the majority attributable to renal sinus/fat (35%) or perinephric fat (31%) involvement. High RNS (>10) was significant in predicting pathologic T3 upstaging (p=0.039) but did not predict high grade (Furhman grade 3-4) disease (p=0.803). While a high nephrometry score trended toward predicting malignancy vs benign disease (p=0.086), a higher mean nephrometry score (7.81 vs. 6.84) significantly predicted malignancy (p=0.015). When controlled for cT1a lesions, tumor location relative to polar lines (L=3 vs. L1+2) was predictive of pT3 upstaging (24 vs. 6%, p=0.03). Age >65 was significantly associated with upstaging (26 vs. 7%, p=0.0001). Conclusions: Surveillance of small renal masses is common but high RNS and age >65 significantly predicted pathologic upstaging. Mean nephrometry score was also useful in predicting malignancy. Nephrometry score may aid in deciding on early surgical intervention.