Ki67 is an independent predictor of oncological outcomes in patients with localized clear-cell renal cell carcinoma

To validate the impact of Ki67 expression on oncological outcomes of patients treated for clinically localized clear-cell renal cell carcinoma (ccRCC).Immunohistochemistry for Ki67 was performed on tissue microarray constructs of patients treated with radical or partial nephrectomy for clinically localized (M0) ccRCC and Ki67 expression10% was considered abnormal. Clinical and pathological data elements were entered into an institutional review board-approved database. The Kaplan-Meier method and Cox regression models were used to analyse disease-free survival (DFS) and cancer-specific survival (CSS) probabilities.Of 401 patients, 59.6% were males. The median (range) age was 58 (17-85) years, follow-up was 22 (0-150) months and time to death was 27 (0-150) months. A total of 20.2% of patients had advanced stage (pT3-T4) and 31% had advanced grade (3-4) disease. Abnormal expression of Ki67 was seen in 6.5% of our cohort and was associated with adverse pathological features (P0.05). Patients with high expression of Ki67 were found to have 5-year DFS and CSS rates of 67 and 84%, respectively, vs 87 and 95%, respectively, in those with normal expression (P0.001 and P0.05, respectively). In multivariable analyses, adjusting for stage and grade, abnormal Ki67 expression was an independent predictor of DFS (hazard ratio [HR] 3.77, P = 0.011, 95% confidence interval [CI] 1.35-10.52), but not of CSS (HR 3.51 P = 0.137, 95% CI 0.671-18.35).Our findings support the role of Ki67 as a powerful independent predictor of inferior oncological outcomes in patients with ccRCC. Further prospective studies are needed to determine the clinical applicability of these findings.