Improving the prognostic value of histopathological grading and clinical staging in renal cell carcinomas by means of computer‐assisted microscopy

The present work aims to refine prognosis in cases of renal cell carcinoma (RCC) by integrating a variety of parameters with the prognostic information provided by histopathological grading and clinical staging, carried out on a series of 97 RCCs. To this end, Feulgen‐stained RCC cell nuclei were characterized by means of 38 variables describing nuclear DNA ploidy levels and morphology. All of these data were subjected to a principal components analysis. On the basis of this multivariate analysis, Fuhrman grade II was subdivided into grades II− and II+, and Fuhrman grade III into grade III− and III+. The same kind of subcategorization was performed in the case of the T2 and T3 clinical stages. The results show that the classification into grade II− and III− RCCs correspond to a more favourable prognosis than grade II+ and III+, to which shorter survival periods were attributable. Similar results were obtained for the subcategorization of the T2 and T3 clinical stages. Very simple biological characterizations of these grade‐ or stage‐related RCC groups were obtained by means of a decision tree approach applied to the cytometry‐generated variables. The resulting classification rules were validated on a new series of 18 patients and enabled very accurate predictions of survival. Copyright © 1999 John Wiley & Sons, Ltd.