Prognostic significance of Ki-67 immunostaining in nonmetastatic renal cell carcinoma.

Purpose: Fresh tissue samples from nonmetastatic renal cell carcinoma (RCC) patients were analyzed by Ki-67 immunostaining to determine the prognostic significance of this tumor-biologic parameter.

Materials And Methods: In a prospective study, Ki-67 immunostaining was performed on frozen sections of histologically proven node-negative RCC from 58 patients operated on between 1986 and 1988 to examine the method's prognostic value and its association with other clinicopathologic parameters such as tumor stage (pT) and grade (G).

Results: The percentage of Ki-67-positive cells (ie, the proliferation rate [PR]) of all 58 RCC tumors ranged between 1% and 23%, while normal renal tissue exhibited PRs up to 2% only. In almost all cases, the highest PRs were observed in the peripheral zone of malignant tissue close to the normal renal tissue. PR did not correlate with pT, whereas a strongly significant correlation was observed between PR and G, as well as recurrence rate. Twenty-three of 58 patients (39.6%) developed tumor recurrence. Disease-free survival was strongly associated with PR. In a multivariate analysis, G and PR were independent prognostic markers.

Conclusion: The tumor-specific PR obtained by Ki-67 labeling seems to be an independent marker to describe the proliferative activity and aggressiveness of individual tumors. This new tumor-biologic marker detects RCC patients at high risk for recurrent disease, especially in those cases with identical pT and G.