Background: Locally Advanced Breast Cancer (LABC) is still the most common stage found in breast cancer patients in Indonesia. Neoadjuvant Chemotherapy (NAC) is the initial therapy and the main pillar of LABC treatment. NAC could provide less extensive surgery and improve patient’s overall survival to those who achieve a complete pathological response. Ki67 expression is a tumor biomarker representing tumor cell proliferation and has been extensively investigated as a promising predictive and prognostic factor in breast cancer. This study aims to examine the association between Ki67 expression with clinical response of NAC.
Methods: The study was designed as a case-control study in breast cancer patients who received standard anthracycline-based NAC. Clinical and immunohistochemical characteristics before and after NAC were obtained retrospectively. Changes in Ki67 and NAC responses were analyzed. Data were analyzed using SPSS version 23 for Windows
Results: A total of 66 subjects were analyzed. About 33 subjects were in good clinical response and 33 subjects were in poor clinical response. Chi-square analysis showed that no significant differences were found in the pre-treatment Ki67 expression between good and poor clinical response group, whereas a low post-treatment Ki67 expression (Ki67 <20%) was correlated with a good clinical response to NAC (p=0.027). Further analysis also showed that a decrease of Ki67 expression greater than 12.5% after treatment was significantly correlated with good clinical response (p=0.007; OR=4.67; 95%CI=1.45-15.08). In multivariate analysis, a decrease in Ki67 was significantly correlated to response in NAC (p=0.037).
Conclusion: Decreased in Ki67 greater than 12.5% was correlated with good clinical response of Anthracycline-based NAC in LABC.