A proposal for reclassification of the Fuhrman grading system in patients with clear cell renal cell carcinoma.

BACKGROUND: The conventional Fuhrman grading system, which categorizes renal cell carcinoma (RCC) with grades I, II, III, and IV, is the most widely used predictor assessment of RCC cancer-specific mortality (CSM).

OBJECTIVES: The aim of this study was to test the prognostic ability of simplified Fuhrman grading schemes (FGSs) that rely on two- or three-tiered classifications.

DESIGN, SETTING, AND PARTICIPANTS: The current study addressed a population of 14064 patients with clear cell RCC who were treated with partial or radical nephrectomy between 1988-2004, within nine Surveillance, Epidemiology, and End Results (SEER) cancer registries.

MEASUREMENTS: Univariable and multivariable analyses as well as prognostic accuracy analyses were performed for various FGSs to test their ability to predict CSM rates. The conventional four-tiered FGS was compared to a modified two-tiered FGS in which grades I and II and grades III and IV were combined. A second simplified three-tiered FGS in which grades I and II were combined but grades III and IV were kept separate was also tested.

RESULTS AND LIMITATIONS: The overall 5-yr CSM-free rate was 81.5%. All three FGSs achieved independent predictor status in multivariable analyses. Prognostic accuracy of multivariable models that relied on various FGSs was 83.6% for the modified two-tiered FGS and 83.8% for both the conventional four-tiered and the modified three-tiered FGS.

CONCLUSIONS: Our findings indicate that the simplified FGSs perform equally as well as the conventional four-tiered FGS. The use of simplified grading schemes may represent an advantage for pathologists as well as for clinicians caring for patients with RCC.