High R.E.N.A.L. Nephrometry scores are associated with pathologic upstaging of clinical T1 renal-cell carcinomas in radical nephrectomy specimens: implications for nephron-sparing surgery.

BACKGROUND AND PURPOSE: The R.E.N.A.L. Nephrometry Score (RNS) was developed to standardize the reporting of anatomic information of a renal mass. This study aimed to identify the association of preoperative clinical and tumor features assessed by the RNS with pathologic upstaging of clinical T1 renal-cell carcinomas (RCCs) in complete en bloc radical nephrectomy (RN) specimens.

PATIENTS AND METHODS: A review was performed for 65 consecutive patients (2005-2013) who underwent RNs for a unilateral clinical T1N0M0 RCC. The RNS was measured in all patients based on preoperative CT scans. Pathologic review was performed to identify patients with final pathologic upstaging. Associations were assessed with the Fisher exact test, Student t test, and Wilcoxon rank sum test.

RESULTS: Of the 65 patients (41 male, mean age 59 years), 4 (6%) patients were upstaged to pT2 and 16 (25%) were upstaged to pT3a and above in the final histologic evaluation. Upstaged patients were not significantly different from those without in terms of age, sex, race, surgical approach, side of surgery, Fuhrman grade, and histologic cell type. Independent tumor features associated with pathologic upstaging were (R) tumor diameter (P=0.021), and (L) central location within polar lines (P=0.010). Tumors that were upstaged had a higher median total RNS than those without (10 vs 9, P=0.010). Complex tumors, with RNS≥10, were associated with significantly increased risk of upstaging compared with low and intermediate complexity categories (RNS<10) (relative risk=2.56, 95% confidence interval 1.22-5.37, P=0.014).

CONCLUSIONS: A higher RNS was associated with an increased risk of upstaging in clinical T1 cancers, predominantly from perinephric or sinus fat invasion in RN pathologic specimens. This may have implications on the selection of surgical option for the clinical T1 renal mass.