What attempts have been made to simplify the Fuhrman grading system for renal cell carcinoma (RCC)?

Updated: Jul 02, 2019
  • Author: YiFen Zhang, MD, PhD; Chief Editor: Liang Cheng, MD  more...
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Some researchers have tried to simplify the Fuhrman grading system in order to improve interobserver reproducibility. For example, Zisman et al introduced a two-tiered grading system by grouping conventional Fuhrman grades 1 and 2 into grade 1 and grouping grades 3 and 4 into grade 2. [12] Ficarra et al suggested a simplified model that consisted of grouping grades 1 and 2 as grade 1 but with unchanged groupings of grades 3 and 4 into a three-tiered grading system. [16]

Sun et al compared the simplified Fuhrman grading (ie, two-tiered [12] and three-tiered [16] ) grading systems with a four-tiered grading system and confirmed that the two-tiered and three-tiered grading systems are equally as valuable as the conventional four-tiered Furman grading system based on accuracy criteria in ccRCC. [17] Moreover, a large European study showed that a modified two-tiered Fuhrman grading system has virtually equal accuracy relative to the conventional four-tiered Fuhrman grading system in predicting cancer-specific mortality. [18]  Studies by Smith et al and Becker et al also found that the simplified two-tiered or three-tiered Fuhrman grading system performs similarly to the conventional system. [19, 20]

Mitotic activity is absent or rare in grade 1 and 2 tumors; mitoses are usually readily identified in grade 3 and 4 cases. Grade is assigned based on the highest grade present. Scattered cells may be discounted, but if several cells within a single high-power focus have high-grade characteristics, then the tumor should be graded accordingly. The majority of tumors are nuclear grades 2 and 3; grade 1 tumors are less common (< 5%), and grade 4 tumors account for 5-10% of cases. [9]

Nuclear grade has been shown to be independent of tumor type as a prognostic factor, but its value in specific histologic subtypes of renal cell carcinoma (RCC) remains in question.

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