Abstract
We compared the ability of original nuclear grades from surgical pathology reports and grades reviewed by a urologic pathologist to predict death due to renal cell carcinoma (RCC) for 2,042 patients treated with radical nephrectomy between January 1970 and December 1998. Reviewed grade 1 tumors had small, round nuclei with inconspicuous nucleoli visible at x400; grade 2 contained round to slightly irregular nuclei with mildly enlarged nucleoli visible at x200; grade 3 had round to irregular nuclei with prominent nucleoli visible at x100; grade 4 contained enlarged pleomorphic or giant cells. Predictive abilities were compared using R values from Cox proportional hazards models. There were 1,733 (84.87%) clear cell, 222 (10.87%) papillary, and 87 (4.26%) chromophobe tumors. Reviewed grades were more predictive of death due to RCC than original grades for clear cell (R, 21% vs 16%), papillary (R, 16% vs 13%), and chromophobe (R, 39% vs 27%) RCC. Among patients with clear cell and papillary RCC, this difference was apparent even after adjusting for the 1997 TNM stage. Standardized nuclear grades were more predictive of death due to RCC than nonstandardized grades for all subtypes studied.
Introduction
The importance of nuclear grading in renal cell carcinoma (RCC) is well documented. Although several grading systems have been proposed, there is no consensus about which system provides the most information to predict clinically important outcomes. In 1997, an international consensus conference on RCC sponsored by the Union Internationale Contre le Cancer (UICC) and the American Joint Committee on Cancer (AJCC) outlined recommendations for the grading of RCC. Conference participants proposed that a grading system be based on standardized and reproducible criteria that reflect the heterogeneity of nuclear and nucleolar features within a tumor. These criteria should be assessed in RCC stratified by histologic subtype, excluding benign lesions such as oncocytoma. Last, each grade should result in significant differences in patient outcome, both univariately and after adjusting for important clinical and pathologic features.
Our objective was to apply a grading system for RCC that met the recommendations proposed by the UICC and AJCC. We compared the ability of nonstandardized grades taken from surgical pathology reports to grades reviewed by a urologic pathologist (J.C.C.) using standardized nuclear and nucleolar features to predict death due to RCC among 2,042 patients treated with a radical nephrectomy for clear cell, papillary, or chromophobe RCC.