Elevated Ki-67 (MIB-1) expression as an independent predictor for unfavorable pathologic outcomes and biochemical recurrence after radical prostatectomy in patients with localized prostate cancer: A propensity score matched study

Background: Ki-67 is known to be useful in estimating the fraction of proliferation tumor cells in various malignancies. We tried to investigate clinical association of Ki-67 (MIB-1) expression with the oncological outcomes in patients with localized prostate cancer (PCa) after the radical prostatectomy (RP). Materials and Methods: We retrospectively analyzed the data of 1,561 patients who underwent RP for localized PCa. According to the propensity score having Ki-67 expression, 183 patients with positive Ki-67 expression were matched to 549 patients without Ki-67 expression. By using multivariate Cox-proportional hazards models and logistic regression tests, the prognostic value of each variable was tested. Results: After propensity score matching, positive Ki-67 group showed significant worse clinical characteristics and pathologic outcomes than negative Ki-67 group. The multivariate analysis showed that the Ki-67 expression was significantly associated with several adverse pathologic outcomes including higher pathologic stage (p = 0.006), higher grade group (p = 0.005), seminal vesicle invasion (p = 0.036), and positive surgical margin (p = 0.025). The group with Ki-67 expression showed significant worse biochemical recurrence-free survival (p