Growth fractions of human renal cell carcinoma defined by monoclonal antibody Ki-67. Predictive values for prognosis

BACKGROUND: We used immunohistochemical techniques to elucidate the role of growth fractions of renal cell carcinoma in the clinicopathology of the condition and patient survival. METHODS: Fifty-two fresh-frozen nephrectomy specimens were immunostained with Ki-67 monoclonal antibody. Ki-67 indexes were determined to examine the relationship between tumor size, grade, stage and survival curve. This study included 43 men and nine women with the mean age 58.4 +/- 11.7 years, who had been followed up for 39 +/- 25 months. RESULTS: The Ki-67 index ranged from 0.6 to 14.1%, averaging 4.6 +/- 5.8%. It was 2.8 +/- 2.4% in tumors <5 cm, 4.7 +/- 3.6% in tumors > or =5 cm and 7.1 +/- 9.0% in tumors > or =10 cm. The Ki-67 index of grades 1, 2 and 3 tumors was 2.3 +/- 1.1%, 3.3 +/- 2.7% and 12.0 +/- 10.4%, respectively. Grade 3 tumors had a significantly higher Ki-67 index than grade 1 or grade 2 tumors. There was no correlation between the Ki-67 index and tumor stage. Patients with a Ki-67 index < 5.6% had a better prognosis than those with an index > 5.6% (P=0.029). However, multivariate analysis demonstrated that tumor size (P=0.034) and grade (P=0.038) were higher in hazard ratio than the Ki-67 index. CONCLUSIONS: Most renal cell carcinomas had low growth fractions. Although a high Ki-67 index should indicate a poor prognosis, Ki-67 did not correlate to metastasis. We believe it is necessary to investigate the factors, other than growth potential, that affect metastasis.