Prognostic role of Ki-67 score in localized prostate cancer: A systematic review and meta-analysis

Abstract

Background: Ki-67 for quantifying tumor proliferation is widely used. In localized prostate cancer (PCa), despite a suggested predictive role of Ki-67 for outcomes after therapies, it has not been incorporated into clinical practice. Herein, we conduct a systematic review and meta-analysis of the literature reporting the association of Ki-67 and disease outcomes in PCa treated radically.

Methods: Medline and EMBASE databases were searched without date or language restrictions, using "KI67" and "prostate cancer" MeSH terms. Studies reporting Ki-67 association with clinical outcomes (disease-free survival [DFS], biochemical failure-free survival, rate of distant metastases [DM], disease-specific survival [DSS], or overall survival [OS], or all of these) in patients with PCa managed actively were included, and relevant data extracted by 2 independent reviewers. Odds ratios (OR) were weighted and pooled in a meta-analysis using Mantel-Haenszel random-effect modeling.

Results: Twenty-one studies comprising 5,419 patients met eligibility for analysis, and 67.6% of patients had low Ki-67. Mean Ki-67 was 6.14%. High Ki-67 was strongly associated with worse clinical outcomes. DFS was better in those patients with low Ki-67 at 5 and 10 years (OR = 0.32, 95% CI: 0.23-0.44, P<0.00001; OR = 0.31, 95% CI: 0.20-0.48, P<0.00001). Similarly, low Ki-67 was related to improved DSS at 5 and 10 years (OR = 0.15, 95% CI: 0.10-0.21, P<0.00001; OR = 0.16, 95% CI: 0.06-0.40, P<0.00001). Association between low Ki-67 scores with improved OS (OR = 0.47; 95% CI: 0.37-0.61; P<0.00001) and high Ki-67 scores with DM at 5 years (OR = 4.07; 95% CI: 2.52-6.58; P<0.00001) was consistently observed.

Conclusions: High Ki-67 expression in localized PCa is a factor of poor prognosis for DSS, biochemical failure-free survival, DFS, DM, and OS after curative-intent treatments. Incorporation into clinical routine of this widely available and standardized biomarker should be strongly considered.

Keywords: Ki-67; Meta-analysis; Prostate cancer.