Our objective was to test whether Fuhrman grade [corrected] (FG) is applicable in the context of chromophobe renal cell carcinoma patients treated with partial and radical nephrectomy. Patients (n=1862) with chromophobe renal cell carcinoma treated with partial and radical nephrectomy were identified within the Surveillance, Epidemiology, and End Results (1988-2008). Univariable and multivariable Cox regression analyses were fitted to predict cancer-specific mortality. Discriminant properties were assessed for the conventional four-tiered FG scheme. Additionally, discrimination of the three-tiered FG scheme (1-2 vs 3 vs 4) and the two-tiered FG scheme (1-2 vs 3-4) was also assessed. The statistical significance of the differences in accuracy estimates was compared using the Mantel-Haenszel test. A total of 65 of the 1862 died of the disease. The overall 5-year cancer-specific mortality-free survival rate was 94.8% (95% confidence interval: 93.5-96.2). In univariable analyses, none of the FG strata were significantly associated with cancer-specific mortality. Furthermore, FG was less informative (63%) than tumor size (72%) and tumor stage (69%), using measures of discrimination in univariable analyses. After accounting for all covariates, prediction of 5-year cancer-specific mortality was 79.0% vs 80.3% accurate, respectively, with vs without the consideration of FG (P=0.01). Similar discrimination estimates were obtained for the modified three-tiered FG scheme (78.5%; P=0.009) and the modified two-tiered FG scheme (79.5%; P=0.02). In conclusion, FG is not an informative predictor of prognosis, defined as cancer-specific mortality, after partial and radical nephrectomy for chromophobe renal cell carcinoma patients.
