High Ki-67 Expression is a Poor Prognostic Indicator of 5-Year Survival in Patients with Invasive Breast Cancer

Objective: Ki-67 is a biomarker that reflects cell proliferation. Despite a clear understanding of the protein’s structure and properties, its functional role remains elusive. We conducted the present study to assess the prognostic value of Ki-67 in breast cancer (BC).
Methods: We enrolled 164 individuals in this study: 30 patients with benign tumors and 134 with invasive BC. Immunohistochemistry (IHC) was used to detect Ki-67 expression The prognostic value of Ki-67 for 5-year recurrence-free survival (RFS) could be analyzed in 134 BC patients.
Results: Ki-67 expression showed significant differences with the tumor grade, lymph node (LN) status, HER2 status and hormone receptor (HR) status (all P<0.05). When Ki-67 11% was used as cutoff to divide the 134 cases into two groups, with high and low expression, the patients in former had a significantly higher 5-year recurrence rate (37.1% vs 8.1%, P=0.001) and a worse RFS (log-rank test, P=0.0017) than those in low Ki-67 expression group. Ki-67 was an independent prognostic predictor of 5-year RFS in both univariate and multivariate analyses.
Conclusions: Ki-67 can be used as a negative predictor of 5-year RFS of patients with invasive BC.