The contemporary classification of renal cell carcinoma has prognostic significance

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Prognosis of renal cell carcinomas depends on a variety of factors such as local extension (pathologic stage), metastatic spread, tumor grade, DNA ploidy, and tumor cell proliferation. In a given case, however, it is not possible to predict prognosis based on the above parameters. In recent years, considerable information has been available regarding the relationship of morphologic features of renal cell carcinoma with specific genetic abnormalities. This has provided impetus for developing a combined morphologic and genetic classification of renal cell carcinoma. In 1996, a consensus of a histopathologic classification based on genetic abnormalities was proposed at a Heidelberg workshop. Subsequently in 1997, at a WHO/UICC sponsored-workshop on renal cell carcinoma, held in Rochester, Minnesota, a similar classification scheme was proposed. According to this classification, four distinct renal cell carcinoma types were identified. These included clear cell or conventional, papillary, chromophobe, and collecting duct renal cell carcinoma. The real value of a tumor classification depends upon recognition of specific subtypes, which appear to have distinctly different clinical behavior. In order to evaluate the relevance of the Heidelberg classification of renal cell carcinoma to prognosis, Ljungberg et al. retrospectively studied 186 cases of renal carcinoma according to the guidelines of Heidelberg classification. All patients were treated by nephrectomy and were staged by TNM system. The follow-up time in these patients ranged from 44 to 174 months. On histologic evaluation, the carcinomas were classified as follows: conventional carcinoma 145, papillary 25, chromophobe 12, and unclassified 4. There was no significant difference in the tumor size in the various categories. Conventional carcinoma had the highest rate of metastatic disease at presentation (37%), as compared to papillary carcinoma (16%) and chromophobe (8%). The 5-year survival rate was also significantly different in the various subtypes: 43% for conventional renal carcinoma, 61% for papillary type, and 91% for chromophobe carcinoma. Thus, the results of this study show that classification of a renal tumor, based on the specific morphologic as well as genetic subtypes or renal cell carcinoma as defined in the Heidelberg classification, has significant prognostic implications. Other investigators have also shown similar prognostic utility for the contemporary classification system for renal cell carcinoma.

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