Grading of human renal adenocarcinoma.

One hundred and thirty-eight adenocarcinomas of human kidney were assessed histologically with special reference to the tumor malignancy as indicated by the 5-year survival of the patients. Four different grading systems were used; the classification based on the histologic type of tumor growth, the grading of malignancy according to Arner et al., the grading based on the nuclear structure of carcinoma cells and finally a combined grading system based on the nuclear structure and the demarcation of the tumor from the surround tissue. The histologic type of growth was observed to be an inappropriate basis for grading of renal carcinoma. The grading system of Arner et al. was an appropriate method of malignancy grading despite its somewhat low reproducibility. The grading system based on the nuclear structure of the tumor cells was an accurate measure of the intrinsic malignancy of renal carcinoma and gave an excellent correlation between tumor grade and the 5-year survival rate of the patients. The combined grading system was an equally accurate method in estimating the 5-year prognosis of ranal carcinomas and indicated that the poor demarcation of the tumor from the surroundings in an unfavorable prognostic sign.