Importance of Ki-67 in human epidermal growth factor receptor 2 positive breast cancer

Abstract

Purpose: The aim of this study was to evaluate the importance of Ki-67 in Human Epidermal Growth Factor Receptor 2 (Her-2) positive breast cancer patients. Methods: We reviewed the records of patients diagnosed with Her-2-positive non-metastatic breast cancer between 2005 and 2011. Paraffin-embedded tissue samples were stained with MIB-1 mouse monoclonal antibody to find Ki-67 levels. Patients were grouped as low Ki-67 <20% and high Ki-67 ?20%. Demographic and clinical features were compared. Results: One hundred and six patients were included in the study. Median follow up time was 41 months (range 15-100). Median age was 49.5 years (range 29-79). Twenty-nine patients (27.4%) were in the Ki-67 low group. Demographic features were similar in both groups. Lymphovas-cular invasion was more frequent in the Ki-67 high group, and hormone receptor (HR) positivity was more frequent in the Ki-67 low group (p=0.03, p=0.03, respectively). Recurrence rate was not significantly different in both groups (p=0.36). T stage (p=0.02), stage (p<0.01), lymphovascular invasion (p=0.02), ER status (p=0.02), and HR status (p<0.01) were related with recurrence. In multivariate analysis, stage and HR negativity were independent factors for recurrence (p<0.01, p=0.01, respectively). Recurrence sites were also similar in both groups. Survival rates at the third year for Ki-67 low group and Ki-67 high group were 94% and 92%, respectively. Conclusion: Her-2 positive patients with low Ki-67 and high Ki-67 had similar demographic and pathologic features except lymphovascular invasion and HR status. HR status was an important f actor f or disease course. Clinical course was determined by HR status rather than Ki-67.