Simplification of the Fuhrman grading system for renal cell carcinoma

The Fuhrman grading system (FGS) is the most widely utilized pathological classification and predictor of renal cell carcinoma (RCC) prognosis. The aim of this study was to test the prognostic ability of a simplified two-tier FGS.

We reviewed the data of 509 patients with clear cell RCC who underwent radical or partial nephrectomy between January 1994 and April 2007. The conventional four-tier (I, II, III, IV) FGS was compared to a simplified two-tier FGS in which grades I and II were combined (low grade) and grades III and IV were combined (high grade). Cancer-specific survival (CSS) was calculated for each patient. Univariate and multivariate analyses were used in combination with area under the curve (AUC) of receiver operating characteristic curves to compare prognostic accuracies between grading schemes.

Median follow up was 81.6 months. Using the conventional FGS, the 5 year CSS for Fuhrman grades I, II, III, and IV were 74.1%, 76.0%, 57.3%, and 40.7%, respectively (p < 0.001). Using the simplified two-tier FGS, the 5 year CSS for low grade and high grade were 75.5% and 54.7%, respectively (p < 0.001). Both FGSs achieved independent predictor status in multivariate analyses. Prognostic accuracy of multivariate models between the two FGSs had nearly identical AUCs, with a c-statistic of 0.769 and 0.716 for the two-tier and conventional systems, respectively.

Our findings indicate that the simplified FGS performs similarly to the conventional system. The use of this simplified system may promote greater continuity of pathological interpretation as well as provide a more simplified approach for clinician utilization.