title: Simplification of the Fuhrman grading system for renal cell carcinoma.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Division of Urology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Zachary L
authors.initials: ZL
authors.lastname: Smith
authors.forename: Eugene J
authors.initials: EJ
authors.lastname: Pietzak
authors.forename: Chelsey K
authors.initials: CK
authors.lastname: Meise
authors.forename: Keith
authors.initials: K
authors.lastname: Van Arsdalen
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Wein
authors.forename: S Bruce
authors.initials: SB
authors.lastname: Malkowicz
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Guzzo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D002292:Carcinoma, Renal Cell / Q000473:pathology* / Q000601:surgery; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading / Q000379:methods; D009364:Neoplasm Recurrence, Local / Q000473:pathology*; D009392:Nephrectomy; D012372:ROC Curve; D012189:Retrospective Studies; D015996:Survival Rate; D047368:Tumor Burden